Salt, acid generator, resist composition and method for producing resist pattern

ABSTRACT

Disclosed are a salt represented by formula (I), an acid generator and a resist composition: 
     
       
         
         
             
             
         
       
     
     wherein Q 1  and Q 2  each represent a fluorine atom or a perfluoroalkyl group; R 11  and R 12  each represent a hydrogen atom, a fluorine atom or a perfluoroalkyl group; z represents an integer of 0 to 6; X 0  represents *—CO—O—, *—O—CO—, etc.; L 1  represents a single bond or a hydrocarbon group which may have a substituent; Ar represents an aromatic hydrocarbon group which may have a substituent; X 1  represents an oxygen atom or a sulfur atom; R 1  represents a halogen atom or a haloalkyl group; R 2  represents a halogen atom, a hydroxy group, a haloalkyl group or an alkyl group; m1 represents an integer of 1 to 6; m2 represents an integer of 0 to 4; and Z +  represents an organic cation.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a salt, an acid generator, a resistcomposition and a method for producing a resist pattern.

Description of the Related Art

JP 2018-025789 A mentions salts represented by the following formulas,and resist compositions comprising the salts as acid generators,respectively.

JP 2019-053287 A mentions salts represented by the following formulas,and resist compositions comprising the salts as acid generators,respectively.

SUMMARY OF THE INVENTION

The present invention provides a salt forming a resist pattern with CDuniformity (CDU) which is better than that of a resist pattern formedfrom the resist compositions comprising the salts mentioned above.

The present invention includes the following inventions.

[1] A salt represented by formula (I):

wherein, in formula (I),

Q¹ and Q² each independently represent a fluorine atom or aperfluoroalkyl group having 1 to 6 carbon atoms,

R¹¹ and R¹² each independently represent a hydrogen atom, a fluorineatom or a perfluoroalkyl group having 1 to 6 carbon atoms,

z represents an integer of 0 to 6, and when z is 2 or more, a pluralityof R¹¹ and R¹² may be the same or different from each other,

X⁰ represents *—CO—O—, *—O—CO—, *—O—CO—O— or *—O—, and * represents abonding site to C(R¹¹) (R¹²) or C(Q¹) (Q²),

L¹ represents a single bond or a hydrocarbon group having 1 to 28 carbonatoms which may have a substituent, and —CH₂— included in thehydrocarbon group may be replaced by —O—, —S—, —SO₂— or —CO—,

Ar represents an aromatic hydrocarbon group having 6 to 18 carbon atomswhich may have a substituent,

X¹ represents an oxygen atom or a sulfur atom,

R¹ represents a halogen atom or a haloalkyl group having 1 to 12 carbonatoms,

R² represents a halogen atom, a hydroxy group, a haloalkyl group having1 to 12 carbon atoms or an alkyl group having 1 to 12 carbon atoms, and—CH₂— included in the haloalkyl group and the alkyl group may bereplaced by —O— or —CO—,

m1 represents an integer of 1 to 6, and when m1 is 2 or more, aplurality of groups in parentheses may be the same or different fromeach other,

m2 represents an integer of 0 to 4, and when m2 is 2 or more, aplurality of R² may be the same or different from each other, and

Z⁺ represents an organic cation.

[2] The salt according to [1], wherein L1 represents a single bond or*-L²-CO—O— (L² represents a cyclic hydrocarbon group having 3 to 18carbon atoms or a group obtained by combining a cyclic hydrocarbon grouphaving 3 to 18 carbon atoms with an alkanediyl group having 1 to 4carbon atoms, the cyclic hydrocarbon group may have a substituent, —CH₂—included in the cyclic hydrocarbon group may be replaced by —O—, —S—,—CO— or —SO₂—, —CH₂— included in the alkanediyl group may be replaced by—O— or —CO—, and * represents a bonding site to X⁰).[3] The salt according to [1] or [2], wherein Ar is an aromatichydrocarbon group having 6 to 10 carbon atoms which may have asubstituent.[4] The salt according to any one of [1] to [3], wherein X¹ is an oxygenatom.[5] The salt according to any one of [1] to [4], wherein R¹ is an iodineatom, a fluorine atom or a perfluoroalkyl group having 1 to 3 carbonatoms.[6] The salt according to any one of [1] to [5], wherein R² is an iodineatom, a fluorine atom, a hydroxy group, a perfluoroalkyl group having 1to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms.[7] An acid generator comprising the salt according to any one of [1] to[6].[8] A resist composition comprising the acid generator according to [7]and a resin having an acid-labile group.[9] The resist composition according to [8], wherein the resin having anacid-labile group includes at least one selected from the groupconsisting of a structural unit represented by formula (a1-0), astructural unit represented by formula (a1-1) and a structural unitrepresented by formula (a1-2):

wherein, in formula (a1-0), formula (a1-1) and formula (a1-2),

L^(a01), L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *represents a bonding site to —CO—,

R^(a01), R^(a4) and R^(a5) each independently represent a hydrogen atom,a halogen atom, or an alkyl group having 1 to 6 carbon atoms which mayhave a halogen atom,

R^(a02), R^(a03) and R^(a04) each independently represent an alkyl grouphaving 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, or a group obtained by combining these groups,

R^(a6) and R^(a7) each independently represent an alkyl group having 1to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, analicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatichydrocarbon group having 6 to 18 carbon atoms, or a group formed bycombining these groups,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

[10] The resist composition according to [8] or [9], wherein the resinhaving an acid-labile group includes a structural unit represented byformula (a2-A):

wherein, in formula (a2-A),

R^(a50) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom,

R^(a51) represents a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,an alkoxyalkyl group having 2 to 12 carbon atoms, an alkoxyalkoxy grouphaving 2 to 12 carbon atoms, an alkylcarbonyl group having 2 to 4 carbonatoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, anacryloyloxy group or a methacryloyloxy group,

A^(a50) represents a single bond or *—X^(a51)-(A^(a52)-X^(a52)) and *represents a bonding site to carbon atoms to which —R^(a50) is bonded,

A^(a52) represents an alkanediyl group having 1 to 6 carbon atoms,

X^(a51) and X^(a52) each independently represent —O—, —CO—O— or —O—CO—,

nb represents 0 or 1, and

mb represents an integer of 0 to 4, and when mb is an integer of 2 ormore, a plurality of R^(a51) may be the same or different from eachother.

[11] The resist composition according to any one of [8] to [10], furthercomprising a salt generating an acid having an acidity lower than thatof an acid generated from the acid generator.[12] A method for producing a resist pattern, which comprises:

(1) a step of applying the resist composition according to any one of[8] to [11] on a substrate,

(2) a step of drying the applied resist composition to form acomposition layer,

(3) a step of exposing the composition layer,

(4) a step of heating the exposed composition layer, and

(5) a step of developing the heated composition layer.

It is possible to produce a resist pattern with satisfactory CDuniformity (CDU) by using a resist composition comprising a salt of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In the present specification, “(meth)acrylic monomer” means “at leastone of acrylic monomer and methacrylic monomer”. Notations such as“(meth)acrylate” and “(meth)acrylic acid” mean the same thing. In groupsmentioned in the present specification, regarding groups capable ofhaving both a linear structure and a branched structure, they may haveeither the linear or branched structure. When —CH₂— included in thehydrocarbon group or the like is replaced by —O—, —S—, —CO—, or SO₂—,the same examples shall apply for each group. “Combined group” means agroup in which two or more exemplified groups are bonded, and valencesof those groups may be appropriately changed depending on a bondingform. “derived” or “induced” means that a polymerizable C═C bondincluded in the molecule becomes a single bond (a —C—C— group) bypolymerization. When stereoisomers exist, all stereoisomers areincluded.

[Salt Represented by Formula (I)]

The present invention relates to a salt represented by formula (I)(hereinafter sometimes referred to as “salt (I)”).

Of the salt (I), the side having negative charge is sometimes referredto as “anion (I)”, and the side having positive charge is sometimesreferred to as “cation (I)”:

wherein all symbols are the same as defined above.

In formula (I), examples of the perfluoroalkyl group as for Q¹, Q², R¹¹and R¹² include a trifluoromethyl group, a perfluoroethyl group, aperfluoropropyl group, a perfluoroisopropyl group, a perfluorobutylgroup, a perfluorosec-butyl group, a perfluorotert-butyl group, aperfluoropentyl group, a perfluorohexyl group and the like. The numberof carbon atoms of the perfluoroalkyl group is preferably 1 to 4, andmore preferably 1 to 3.

Preferably, Q¹ and Q² are each independently a trifluoromethyl group ora fluorine atom, and more preferably a fluorine atom.

Preferably, R¹¹ and R¹² are each independently a hydrogen atom, afluorine atom or a trifluoromethyl group, and more preferably a hydrogenatom or a trifluoromethyl group.

z is preferably 0 or 1.

X⁰ is preferably *—CO—O—, *—O—CO—O— or *—O—CO—, and more preferably*—CO—O— or *—O—CO— (*represents a bonding site to C(R¹¹) (R¹²) or C(Q¹)(Q²)).

Examples of the hydrocarbon group in L1 include a divalent chainhydrocarbon group such as an alkanediyl group, a monocyclic orpolycyclic (including a spiro ring) divalent alicyclic hydrocarbongroup, a divalent aromatic hydrocarbon group and the like, and it may bea group obtained by combining two or more groups of these groups (e.g.,a divalent hydrocarbon group formed from an alicyclic hydrocarbon groupand an alkanediyl group).

Examples of the alkanediyl group include linear alkanediyl groups suchas a methylene group, an ethylene group, a propane-1,3-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a heptane-1,7-diyl group, an octane-1,8-diyl group, anonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diylgroup, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and a heptadecane-1,17-diyl group, and

branched alkanediyl groups such as an ethane-1,1-diyl group, apropane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diylgroup, a pentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

The number of carbon atoms of the chain hydrocarbon group is preferably1 to 18, more preferably 1 to 12, still more preferably 1 to 9, yet morepreferably 1 to 6, and further preferably 1 to 4.

Examples of the monocyclic or polycyclic divalent alicyclic hydrocarbongroup include the following groups and the like. The bonding site can beany position.

Specifically, examples of the alicyclic hydrocarbon group includemonocyclic divalent alicyclic hydrocarbon groups which arecycloalkanediyl groups such as a cyclobutane-1,3-diyl group, acyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group and acyclooctane-1,5-diyl group, and

polycyclic divalent alicyclic hydrocarbon groups such as anorbornane-1,4-diyl group, a norbornane-2,5-diyl group, anadamantane-1,5-diyl group and an adamantane-2,6-diyl group.

The number of carbon atoms of the alicyclic hydrocarbon group ispreferably 3 to 18, more preferably 3 to 16, and still more preferably 3to 12.

Examples of the divalent aromatic hydrocarbon group include aromatichydrocarbon groups, for example, arylene groups such as a phenylenegroup, a naphthylene group, an anthrylene group, a biphenylene group anda phenanthrylene group. The number of carbon atoms of the aromatichydrocarbon group is preferably 6 to 18, more preferably 6 to 14, andstill more preferably 6 to 10.

Examples of the group obtained by combining two or more thereof includea group obtained by combining an alicyclic hydrocarbon group with analkanediyl group, a group obtained by combining an aromatic hydrocarbongroup with an alkanediyl group, and a group obtained by combining analicyclic hydrocarbon group with an aromatic hydrocarbon group. Incombination, two or more of alicyclic hydrocarbon groups, aromatichydrocarbon groups and chain hydrocarbon groups may be used incombination. Any group may be bonded to X⁰.

Examples of the group obtained by combining an alicyclic hydrocarbongroup with an alkanediyl group include a -divalent alicyclic hydrocarbongroup-alkanediyl group-, an -alkanediyl group-divalent alicyclichydrocarbon group-alkanediyl group-, an -alkanediyl group-divalentalicyclic hydrocarbon group- and the like.

Examples of the group obtained by combining an aromatic hydrocarbongroup with an alkanediyl group include a -divalent aromatic hydrocarbongroup-alkanediyl group-, an -alkanediyl group-divalent aromatichydrocarbon group-alkanediyl group-, an -alkanediyl group-divalentaromatic hydrocarbon group- and the like.

Examples of the group obtained by combining an alicyclic hydrocarbongroup with an aromatic hydrocarbon group include an -aromatichydrocarbon group-alicyclic hydrocarbon group-, an -alicyclichydrocarbon group-aromatic hydrocarbon group-, an -alicyclic hydrocarbongroup-aromatic hydrocarbon group-alicyclic hydrocarbon group- and thelike.

—CH₂— included in the hydrocarbon group having 1 to 28 carbon atoms asfor L1 may be replaced by —O—, —S—, —SO₂— or —CO—.

When —CH₂— included in the hydrocarbon group having 1 to 28 carbon atomsas for L1 is replaced by —O—, —S—, —SO₂— or —CO—, the number of carbonatoms before replacement is taken as the number of carbon atoms of thehydrocarbon group.

Examples of the group in which —CH₂— included in the hydrocarbon groupis replaced by —O—, —S—, —SO₂— or —CO— include a hydroxy group (a groupin which —CH₂— included in the methyl group is replaced by —O—), acarboxy group (a group in which —CH₂—CH₂— included in the ethyl group isreplaced by —O—CO—), a thiol group (a group in which —CH₂-included inthe methyl group is replaced by —S—), an alkoxy group (a group in which—CH₂— at any position included in the alkyl group is replaced by —O—),an alkylthio group (a group in which —CH₂— at any position included inthe alkyl group is replaced by —S—), an alkoxycarbonyl group (a group inwhich —CH₂—CH₂— at any position included in the alkyl group is replacedby —O—CO—), an alkylcarbonyl group (a group in which —CH₂— at anyposition included in the alkyl group is replaced by —CO—), analkylsulfonyl group (a group in which —CH₂— at any position included inthe alkyl group is replaced by —SO₂—), an alkylcarbonyloxy group (agroup in which —CH₂—CH₂— at any position included in the alkyl group isreplaced by —CO—O—), an alkanediyloxy group (a group in which —CH₂— atany position included in the alkanediyl group is replaced by —O—), analkanediyloxycarbonyl group (a group in which —CH₂—CH₂— at any positionincluded in the alkanediyl group is replaced by —O—CO—), analkanediylcarbonyl group (a group in which —CH₂— at any positionincluded in the alkanediyl group is replaced by —CO—), analkanediylcarbonyloxy group (a group in which —CH₂— at any positionincluded in the alkanediyl group is replaced by —CO—O—), analkanediylsulfonyl group (a group in which —CH₂— at any positionincluded in the alkanediyl group is replaced by —SO₂—), analkanediylthio group (a group in which —CH₂— at any position included inthe alkanediyl group is replaced by —S—), a cycloalkoxy group, acycloalkylalkoxy group, an alkoxycarbonyloxy group, an aromatichydrocarbon group-carbonyloxy group, a group obtained by combining twoor more of these groups, and the like.

Examples of the alkoxy group include alkoxy groups having 1 to 17 carbonatoms, for example, a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxygroup and the like. The number of carbon atoms of the alkoxy group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

Examples of the alkylthio group include alkylthio groups having 1 to 17carbon atoms, for example, a methylthio group, an ethylthio group, apropylthio group, a butylthio group and the like. The number of carbonatoms of the alkylthio group is preferably 1 to 11, more preferably 1 to6, still more preferably 1 to 4, and yet more preferably 1 to 3.

The alkoxycarbonyl group, the alkylcarbonyl group and thealkylcarbonyloxy group represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group include alkoxycarbonyl groupshaving 2 to 17 carbon atoms, for example, a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like. Examples ofthe alkylcarbonyl group include alkylcarbonyl groups having 2 to 18carbon atoms, for example, an acetyl group, a propionyl group and abutyryl group. Examples of the alkylcarbonyloxy group includealkylcarbonyloxy groups having 2 to 17 carbon atoms, for example, anacetyloxy group, a propionyloxy group, a butyryloxy group and the like.The number of carbon atoms of the alkoxycarbonyl group is preferably 2to 11, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of the alkylcarbonylgroup is preferably 2 to 12, more preferably 2 to 6, still morepreferably 2 to 4, and yet more preferably 2 or 3. The number of carbonatoms of the alkylcarbonyloxy group is preferably 2 to 11, morepreferably 2 to 6, still more preferably 2 to 4, and yet more preferably2 or 3.

Examples of the alkylsulfonyl group include alkylsulfonyl groups having1 to 17 carbon atoms, for example, a methylsulfonyl group, anethylsulfonyl group, a propylsulfonyl group and the like. The number ofcarbon atoms of the alkylsulfonyl group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

Examples of the alkanediyloxy group include alkanediyloxy groups having1 to 17 carbon atoms, for example, a methyleneoxy group, an ethyleneoxygroup, a propanediyloxy group, a butanediyloxy group, a pentanediyloxygroup and the like. The number of carbon atoms of the alkanediyloxygroup is preferably 1 to 11, more preferably 1 to 6, still morepreferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkanediyloxycarbonyl group includealkanediyloxycarbonyl groups having 2 to 17 carbon atoms, for example, amethyleneoxycarbonyl group, an ethyleneoxycarbonyl group, apropanediyloxycarbonyl group, a butanediyloxycarbonyl group and thelike. Examples of the alkanediylcarbonyl group includealkanediylcarbonyl groups having 2 to 18 carbon atoms, for example, amethylenecarbonyl group, an ethylenecarbonyl group, apropanediylcarbonyl group, a butanediylcarbonyl group, apentanediylcarbonyl group and the like. Examples of thealkanediylcarbonyloxy group include alkanediylcarbonyloxy groups having2 to 17 carbon atoms, for example, a methylenecarbonyloxy group, anethylenecarbonyloxy group, a propanediylcarbonyloxy group, abutanediylcarbonyloxy group and the like. The number of carbon atoms ofthe alkanediyloxycarbonyl group is preferably 2 to 11, more preferably 2to 6, still more preferably 2 to 4, and yet more preferably 2 or 3. Thenumber of carbon atoms of the alkanediylcarbonyl group is preferably 2to 12, more preferably 2 to 6, still more preferably 2 to 4, and yetmore preferably 2 or 3. The number of carbon atoms of thealkanediylcarbonyloxy group is preferably 2 to 11, more preferably 2 to6, still more preferably 2 to 4, and yet more preferably 2 or 3.

Examples of the alkanediylsulfonyl group include alkanediylsulfonylgroups having 1 to 17 carbon atoms, for example, a methylenesulfonylgroup, an ethylenesulfonyl group, a propylenesulfonyl group and thelike. The number of carbon atoms of the alkanediylsulfonyl group ispreferably 1 to 11, more preferably 1 to 6, still more preferably 1 to4, and yet more preferably 1 to 3.

Examples of the alkanediylthio group include alkanediylthio groupshaving 1 to 17 carbon atoms, for example, a methylenethio group, anethylenethio group, a propylenethio group and the like. The number ofcarbon atoms of the alkanediylthio group is preferably 1 to 11, morepreferably 1 to 6, still more preferably 1 to 4, and yet more preferably1 to 3.

Examples of the cycloalkoxy group include cycloalkoxy groups having 3 to17 carbon atoms, for example, a cyclohexyloxy group and the like.Examples of the cycloalkylalkoxy group include cycloalkylalkoxy groupshaving 4 to 17 carbon atoms, for example, a cyclohexylmethoxy group andthe like. Examples of the alkoxycarbonyloxy group includealkoxycarbonyloxy groups having 2 to 16 carbon atoms, for example, abutoxycarbonyloxy group and the like. Examples of the aromatichydrocarbon group-carbonyloxy group include aromatic hydrocarbongroup-carbonyloxy groups having 7 to 17 carbon atoms, for example, abenzoyloxy group and the like.

Examples of the group in which —CH₂— included in the alicyclichydrocarbon group is replaced by —O—, —S—, —CO— or —SO₂— include thefollowing groups and the like. —O— or —CO— may be replaced by —S— or—SO₂—, respectively. The bonding site can be any position.

Examples of the substituent which may be possessed by L1 include ahydroxy group, a carboxy group, a halogen atom, a cyano group, an alkylgroup having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbonatoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, analkylcarbonyl group having 2 to 13 carbon atoms, an alkylcarbonyloxygroup having 2 to 13 carbon atoms, or a group obtained by combining twoor more of these groups.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkyl group having 1 to 12 carbon atoms include a methylgroup, an ethyl group, a propyl group, an isopropyl group, a butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, a hexylgroup, an octyl group, a nonyl group and the like.

Examples of the alkoxy group having 1 to 12 carbon atoms include amethoxy group, an ethoxy group, a propoxy group, a butoxy group, apentyloxy group, a hexyloxy group, an octyloxy group, a 2-ethylhexyloxygroup, a nonyloxy group, a decyloxy group, an undecyloxy group, adodecyloxy group and the like.

The alkoxycarbonyl group having 2 to 13 carbon atoms, the alkylcarbonylgroup having 2 to 13 carbon atoms and the alkylcarbonyloxy group having2 to 13 carbon atoms represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group having 2 to 13 carbon atoms includea methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl groupand the like, examples of the alkylcarbonyl group having 2 to 13 carbonatoms include an acetyl group, a propionyl group and a butyryl group,and examples of the alkylcarbonyloxy group having 2 to 13 carbon atomsinclude an acetyloxy group, a propionyloxy group, a butyryloxy group andthe like.

The substituent is preferably an alkyl group having 1 to 4 carbon atoms,a hydroxy group or a halogen atom, more preferably an alkyl group having1 to 4 carbon atoms or a halogen atom, and still more preferably amethyl group or a fluorine atom.

L¹ is preferably a single bond, an alkanediyl group having 1 to 8 carbonatoms (in which —CH₂— included in the alkanediyl group may be replacedby —O— or —CO—), a group obtained by combining an alkanediyl grouphaving 1 to 6 carbon atoms with alicyclic hydrocarbon group having 3 to18 carbon atoms which may have a substituent (in which —CH₂-included inthe alkanediyl group may be replaced by —O— or —CO—, and —CH₂— includedin the alicyclic hydrocarbon group may be replaced by —O—, —S—, —SO₂— or—CO—) or a group obtained by combining an alkanediyl group having 1 to 6carbon atoms with an aromatic hydrocarbon group having 6 to 18 carbonatoms which may have a substituent (in which —CH₂-included in thealkanediyl group may be replaced by —O— or —CO—), and more preferably asingle bond, an alkanediyl group having 1 to 6 carbon atoms (in which—CH₂— included in the alkanediyl group may be replaced by —O— or —CO—),a group obtained by combining an alkanediyl group having 1 to 4 carbonatoms with an alicyclic hydrocarbon group having 3 to 18 carbon atomswhich may have a substituent (in which —CH₂-included in the alkanediylgroup may be replaced by —O— or —CO—, and —CH₂— included in thealicyclic hydrocarbon group may be replaced by —O— or —CO—) or a groupobtained by combining an alkanediyl group having 1 to 4 carbon atomswith an aromatic hydrocarbon group having 6 to 18 carbon atoms which mayhave a substituent (in which —CH₂— included in the alkanediyl group maybe replaced by —O— or —CO—).

L1 is also preferably a single bond, *-L²-CO—O— or *-L²-O—CO—O— (L²represents a cyclic hydrocarbon group having 3 to 18 carbon atoms or agroup obtained by combining a cyclic hydrocarbon group having 3 to 18carbon atoms with an alkanediyl group having 1 to 4 carbon atoms, thecyclic hydrocarbon group may have a substituent, —CH₂— included in thecyclic hydrocarbon group may be replaced by —O—, —S—, —CO— or —SO₂—,—CH₂— included in the alkanediyl group may be replaced by —O— or —CO—,and * represents a bonding site to X⁰).

Examples of the combination of an alkanediyl group with an alicyclichydrocarbon group or an aromatic hydrocarbon group herein include a*-alkanediyl group-alicyclic hydrocarbon group or an aromatichydrocarbon group-, a *-alicyclic hydrocarbon group or an aromatichydrocarbon group-alkanediyl group-, a *-alkanediyl group-alicyclichydrocarbon group or an aromatic hydrocarbon group-alkanediyl group- andthe like. * represents a bonding site to X⁰.

Examples of the cyclic hydrocarbon group and the alkanediyl group in L²include the same groups as mentioned above.

L² is preferably a polycyclic divalent cyclic hydrocarbon group having 6to 12 carbon atoms or a group obtained by combining a polycyclicdivalent cyclic hydrocarbon group having 6 to 12 carbon atoms with analkanediyl group having 1 to 4 carbon atoms (the cyclic hydrocarbongroup may have a substituent, —CH₂— included in the cyclic hydrocarbongroup may be replaced by —O—, —S—, —CO— or —SO₂—, and —CH₂— included inthe alkanediyl group may be replaced by —O— or —CO—), more preferably apolycyclic divalent alicyclic hydrocarbon group having 7 to 11 carbonatoms or a group obtained by combining a polycyclic divalent alicyclichydrocarbon group having 7 to 11 carbon atoms with an alkanediyl grouphaving 1 to 3 carbon atoms (—CH₂-included in the alicyclic hydrocarbongroup may be replaced by —O— or —CO—, and —CH₂— included in thealkanediyl group may be replaced by —O— or —CO—), still more preferablya group selected from the group consisting of a group represented by thefollowing formula (L²-1), a group represented by formula (L²-2), a grouprepresented by formula (L²-3) and a group represented by formula (L²-4),or a group obtained by combining a group selected from the groupconsisting of a group represented by the following formula (L²-1), agroup represented by formula (L²-2), a group represented by formula(L²-3) and a group represented by formula (L²-4) with an alkanediylgroup having 1 to 3 carbon atoms (—CH₂— included in the alkanediyl groupmay be replaced by —O— or —CO—), and yet more preferably a grouprepresented by formula (L²-2). * represents a bonding site.

Examples of the aromatic hydrocarbon group in Ar include, in the case ofdivalent, aromatic hydrocarbon groups, for example, arylene groups suchas a phenylene group, a naphthylene group, an anthrylene group, abiphenylene group and a phenanthrylene group. Examples thereof include,in the case of trivalent, aromatic hydrocarbon groups such as abenzenetriyl group, a naphthalenetriyl group, an anthracenetriyl group,a biphenyltriyl group and a phenanthrenetriyl group. Examples thereofinclude, in the case of tetravalent, aromatic hydrocarbon groups such asa benzenetetrayl group, a naphthalenetetrayl group, an anthracenetetraylgroup, a biphenyltetrayl group and a phenanthrenetetrayl group. Examplesthereof include, in the case of pentavalent, aromatic hydrocarbon groupssuch as a benzenepentayl group, a naphthalenepentayl group, ananthracenepentayl group, a biphenylpentayl group and aphenanthrenepentayl group. Examples thereof include, in the case ofhexavalent, aromatic hydrocarbon groups such as a benzenehexayl group, anaphthalenehexayl group, an anthracenehexayl group, a biphenylhexaylgroup and a phenanthrenehexayl group.

The number of carbon atoms of the aromatic hydrocarbon group ispreferably 6 to 18, more preferably 6 to 14, still more preferably 6 to10, and yet more preferably 6.

Examples of the substituent which may be possessed by Ar include ahydroxy group, a carboxy group, a halogen atom, a cyano group, an alkylgroup having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbonatoms, an alkoxycarbonyl group having 2 to 13 carbon atoms, analkylcarbonyl group having 2 to 13 carbon atoms, an alkylcarbonyloxygroup having 2 to 13 carbon atoms, or groups obtained by combining thesegroups.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkyl group having 1 to 12 carbon atoms include a methylgroup, an ethyl group, a propyl group, an isopropyl group, a butylgroup, an isobutyl group, a tert-butyl group, a pentyl group, a hexylgroup, an octyl group, a nonyl group and the like.

Examples of the alkoxy group having 1 to 12 carbon atoms include amethoxy group, an ethoxy group, a propoxy group, a butoxy group, apentyloxy group, a hexyloxy group, an octyloxy group, a 2-ethylhexyloxygroup, a nonyloxy group, a decyloxy group, an undecyloxy group, adodecyloxy group and the like.

The alkoxycarbonyl group having 2 to 13 carbon atoms, the alkylcarbonylgroup having 2 to 13 carbon atoms and the alkylcarbonyloxy group having2 to 13 carbon atoms represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group having 2 to 13 carbon atoms includea methoxycarbonyl group, an ethoxycarbonyl group, a butoxycarbonyl groupand the like, examples of the alkylcarbonyl group having 2 to 13 carbonatoms include an acetyl group, a propionyl group and a butyryl group,and examples of the alkylcarbonyloxy group having 2 to 13 carbon atomsinclude an acetyloxy group, a propionyloxy group, a butyryloxy group andthe like.

The substituent is preferably an alkyl group having 1 to 12 carbonatoms, an alkoxy group having 1 to 12 carbon atoms, a hydroxy group, acarboxy group or a halogen atom, more preferably an alkyl group having 1to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a hydroxygroup or a halogen atom, and still more preferably an alkyl group having1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, ahydroxy group or a halogen atom.

Ar is preferably an aromatic hydrocarbon group having 6 to 14 carbonatoms which may have a substituent, more preferably an aromatichydrocarbon group having 6 to 10 carbon atoms which may have asubstituent, still more preferably an aromatic hydrocarbon group having6 carbon atoms which may have a substituent, and yet more preferably aphenylene group which may have a substituent. The substituent ispreferably an alkyl group having 1 to 12 carbon atoms, an alkoxy grouphaving 1 to 12 carbon atoms, a hydroxy group, a carboxy group or ahalogen atom, more preferably an alkyl group having 1 to 6 carbon atoms,an alkoxy group having 1 to 6 carbon atoms, a hydroxy group or a halogenatom, and still more preferably an alkyl group having 1 to 3 carbonatoms, an alkoxy group having 1 to 3 carbon atoms, a hydroxy group or ahalogen atom.

Examples of the halogen atom as for R¹ and R² include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

The haloalkyl group having 1 to 12 carbon atoms in R¹ and R² representsan alkyl group having 1 to 12 carbon atoms which has a halogen atom, andexamples thereof include an alkyl fluoride group having 1 to 12 carbonatoms, an alkyl chloride group having 1 to 12 carbon atoms, an alkylbromide group having 1 to 12 carbon atoms, an alkyl iodide group having1 to 12 carbon atoms and the like. Examples of the haloalkyl groupinclude a perfluoroalkyl group having 1 to 12 carbon atoms (atrifluoromethyl group, a pentafluoroethyl group, a heptafluoropropylgroup, a nonafluorobutyl group, etc.), a 2,2,2-trifluoroethyl group, a3,3,3-trifluoropropyl group, a 4,4,4-trifluorobutyl group, a3,3,4,4,4-pentafluorobutyl group, a chloromethyl group, a bromomethylgroup, an iodomethyl group and the like. The number of carbon atoms ofthe haloalkyl group is preferably 1 to 9, more preferably 1 to 6, stillmore preferably 1 to 4, and yet more preferably 1 to 3.

Examples of the alkyl group having 1 to 12 carbon atoms as for R²include alkyl groups such as a methyl group, an ethyl group, a propylgroup, an isopropyl group, a butyl group, an isobutyl group, atert-butyl group, a pentyl group, a hexyl group, an octyl group and anonyl group. The number of carbon atoms of the alkyl group is preferably1 to 9, more preferably 1 to 6, still more preferably 1 to 4, and yetmore preferably 1 to 3.

When —CH₂— included in the haloalkyl group or the alkyl grouprepresented by R² is replaced by —O— or —CO—, the number of carbon atomsbefore replacement is taken as the total number of carbon atoms of thehaloalkyl group or the alkyl group. Examples of the replaced groupinclude a hydroxy group (a group in which —CH₂— included in the methylgroup is replaced by —O—), a carboxy group (a group in which —CH₂—CH₂—included in the ethyl group is replaced by —O—CO—), an alkoxy group (agroup in which —CH₂— at any position included in the alkyl group isreplaced by —O—), an alkoxycarbonyl group (a group in which —CH₂—CH₂— atany position included in the alkyl group is replaced by —O—CO—), analkylcarbonyl group (a group in which —CH₂— at any position included inthe alkyl group is replaced by —CO—), an alkylcarbonyloxy group (a groupin which —CH₂—CH₂— at any position included in the alkyl group isreplaced by —CO—O—), a haloalkoxy group (a group in which —CH₂— at anyposition included in the haloalkyl group is replaced by —O—), ahaloalkoxycarbonyl group (a group in which —CH₂—CH₂— at any positionincluded in the haloalkyl group is replaced by —O—CO—), ahaloalkylcarbonyl group (a group in which —CH₂— at any position includedin the haloalkyl group is replaced by —CO—), a haloalkylcarbonyloxygroup (a group in which —CH₂—CH₂— at any position included in thehaloalkyl group is replaced by —CO—O—), and a group obtained bycombining two or more of these groups.

Examples of the alkoxy group include alkoxy groups having 1 to 11 carbonatoms, for example, a methoxy group, an ethoxy group, a propoxy group, abutoxy group, a pentyloxy group, a hexyloxy group, an octyloxy group, a2-ethylhexyloxy group, a nonyloxy group, a decyloxy group, an undecyloxygroup and the like. The number of carbon atoms of the alkoxy group ispreferably 1 to 6, more preferably 1 to 4, and still more preferably 1to 3.

The alkoxycarbonyl group, the alkylcarbonyl group and thealkylcarbonyloxy group represent a group in which a carbonyl group or acarbonyloxy group is bonded to the above-mentioned alkyl group or alkoxygroup.

Examples of the alkoxycarbonyl group include alkoxycarbonyl groupshaving 2 to 11 carbon atoms, for example, a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like; examples ofthe alkylcarbonyl group include alkylcarbonyl groups having 2 to 12carbon atoms, for example, an acetyl group, a propionyl group and abutyryl group; and examples of the alkylcarbonyloxy group includealkylcarbonyloxy groups having 2 to 11 carbon atoms, for example, anacetyloxy group, a propionyloxy group, a butyryloxy group and the like.The number of carbon atoms of the alkoxycarbonyl group is preferably 2to 6, more preferably 2 to 4, and still more preferably 2 or 3. Thenumber of carbon atoms of the alkylcarbonyl group is preferably 2 to 6,more preferably 2 to 4, and still more preferably 2 or 3. The number ofcarbon atoms of the alkylcarbonyloxy group is preferably 2 to 6, morepreferably 2 to 4, and still more preferably 2 or 3.

Examples of the haloalkoxy group, the haloalkoxycarbonyl group, thehaloalkylcarbonyl group and the haloalkylcarbonyloxy group include ahaloalkoxy group having 1 to 11 carbon atoms, a haloalkoxycarbonyl grouphaving 2 to 11 carbon atoms, a haloalkylcarbonyl group having 2 to 12carbon atoms and a haloalkylcarbonyloxy group having 2 to 11 carbonatoms, for example, a group in which one or more hydrogen atoms of theabove-mentioned groups are replaced by a halogen atom.

X¹ is preferably an oxygen atom.

When Ar is an aromatic hydrocarbon group having 6 carbon atoms which mayhave a substituent, the bonding site of X¹ to Ar may be any of theo-position, the m-position and the p-position, with respect to thebonding site of L1. Particularly, when m1 is 1, it is preferable that X¹is bonded at the p-position or the m-position, and more preferable thatX¹ is bonded at the p-position, with respect to the bonding site of L1.When m1 is 2, it is preferable that one X¹ is bonded at the o-positionor the m-position and one X¹ is bonded at the o-position or them-position, and more preferable that two X¹ are bonded at them-position, with respect to the bonding site of L1. When m1 is 3, it ispreferable that two X¹ are bonded at the o-position or the m-positionand one X¹ is bonded at the p-position or the m-position, and morepreferable that two X¹ are bonded at the m-position and one X¹ is bondedat the p-position, with respect to the bonding site of L1. When m1 is 4,it is preferable that two X¹ are bonded at the o-position or them-position and two X¹ are bonded at the p-position or the m-position,and more preferable that two X¹ are bonded at the o-position and two X¹are bonded at the m-position, with respect to the bonding site of L¹.

m1 is preferably 1, 2, 3, 4 or 5, more preferably 1, 2, 3 or 4, andstill more preferably 1, 2 or 4.

m2 is preferably 0, 1, 2 or 4, and more preferably 0, 2 or 4.

R¹ is preferably an iodine atom, a fluorine atom or a haloalkyl grouphaving 1 to 6 carbon atoms, more preferably an iodine atom, a fluorineatom or a perfluoroalkyl group having 1 to 3 carbon atoms, still morepreferably an iodine atom, a fluorine atom or a trifluoromethyl group,and yet more preferably an iodine atom or a fluorine atom.

Preferably, R² represents an iodine atom, a fluorine atom, a hydroxygroup, a haloalkyl group having 1 to 6 carbon atoms or an alkyl grouphaving 1 to 6 carbon atoms (—CH₂-included in the haloalkyl group and thealkyl group may be replaced by —O— or —CO—), more preferably an iodineatom, a fluorine atom, a hydroxy group, an alkyl group having 1 to 4carbon atoms, a haloalkyl group having 1 to 4 carbon atoms or an alkoxygroup having 1 to 3 carbon atoms, still more preferably an iodine atom,a fluorine atom, a hydroxy group, a perfluoroalkyl group having 1 to 3carbon atoms or an alkoxy group having 1 to 3 carbon atoms, and yet morepreferably an iodine atom, a fluorine atom, a hydroxy group, atrifluoromethyl group or a methoxy group.

The bonding site of R¹ to the benzene ring may be any of the o-position,the m-position and the p-position, with respect to the bonding site ofX¹. Particularly, the bonding site of R¹ to the benzene ring ispreferably the m-position or the p-position, with respect to the bondingsite of X¹.

The bonding site of R² to the benzene ring may be any of the o-position,the m-position and the p-position, with respect to the bonding site ofX¹. Particularly, when m2 is 1, the bonding site of R² to the benzenering is preferably the m-position or the p-position, with respect to thebonding site of X¹. When m2 is 2, it is preferable that one bonding siteis the o-position or the m-position and one bonding site is theo-position or the p-position, with respect to the bonding site of X¹.When m2 is 4, it is preferable that two bonding sites are the o-positionor the m-position and two bonding sites are the m-position or thep-position, with respect to the bonding site of X¹.

Examples of the anion (I) include the following anions. Of these, anionsrepresented by formula (Ia-1) to formula (Ia-3), formula (Ia-10) toformula (Ia-20), formula (Ia-23) to formula (Ia-25) and formula (Ia-31)to formula (Ia-42) are preferable.

Examples of the organic cation as for Z⁺ include an organic oniumcation, an organic sulfonium cation, an organic iodonium cation, anorganic ammonium cation, a benzothiazolium cation and an organicphosphonium cation. Of these, an organic sulfonium cation and an organiciodonium cation are preferable, and an aryl sulfonium cation is morepreferable. Specific examples thereof include a cation represented byany one of formula (b2-1) to formula (b2-4) (hereinafter sometimesreferred to as “cation (b2-1)” according to the number of formula).

In formula (b2-1) to formula (b2-4),

R^(b4) to R^(b6) each independently represent a chain hydrocarbon grouphaving 1 to 30 carbon atoms, an alicyclic hydrocarbon group having 3 to36 carbon atoms or an aromatic hydrocarbon group having 6 to 36 carbonatoms, a hydrogen atom included in the chain hydrocarbon group may besubstituted with a hydroxy group, an alkoxy group having 1 to 12 carbonatoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms or anaromatic hydrocarbon group having 6 to 18 carbon atoms, a hydrogen atomincluded in the alicyclic hydrocarbon group may be substituted with ahalogen atom, an aliphatic hydrocarbon group having 1 to 18 carbonatoms, an alkylcarbonyl group having 2 to 4 carbon atoms or aglycidyloxy group, and a hydrogen atom included in the aromatichydrocarbon group may be substituted with a halogen atom, a hydroxygroup, an aliphatic hydrocarbon group having 1 to 18 carbon atoms, analkyl fluoride group having 1 to 12 carbon atoms or an alkoxy grouphaving 1 to 12 carbon atoms.

R^(b4) and R^(b5) may be bonded to each other to form a ring togetherwith sulfur atoms to which R^(b4) and R^(b5) are bonded, and —CH₂—included in the ring may be replaced by —O—, —S— or —CO—,

R^(b7) and R^(b8) each independently represent a halogen atom, a hydroxygroup, an aliphatic hydrocarbon group having 1 to 12 carbon atoms, analkyl fluoride group having 1 to 12 carbon atoms or an alkoxy grouphaving 1 to 12 carbon atoms,

m2 and n2 each independently represent an integer of 0 to 5,

when m2 is 2 or more, a plurality of R^(b7) may be the same ordifferent, and when n2 is 2 or more, a plurality of R^(b8) may be thesame or different,

R^(b9) and R^(b10) each independently represent a chain hydrocarbongroup having 1 to 36 carbon atoms or an alicyclic hydrocarbon grouphaving 3 to 36 carbon atoms,

R^(b9) and R^(b10) may be bonded to each other to form a ring togetherwith sulfur atoms to which R^(b9) and R^(b10) are bonded, and —CH₂—included in the ring may be replaced by —O—, —S— or —CO—,

R^(b11) represents a hydrogen atom, a chain hydrocarbon group having 1to 36 carbon atoms, an alicyclic hydrocarbon group having 3 to 36 carbonatoms or an aromatic hydrocarbon group having 6 to 18 carbon atoms,

R^(b12) represents a chain hydrocarbon group having 1 to 12 carbonatoms, an alicyclic hydrocarbon group having 3 to 18 carbon atoms or anaromatic hydrocarbon group having 6 to 18 carbon atoms, a hydrogen atomincluded in the chain hydrocarbon group may be substituted with anaromatic hydrocarbon group having 6 to 18 carbon atoms, a hydrogen atomincluded in the aromatic hydrocarbon group may be substituted with analkoxy group having 1 to 12 carbon atoms or an alkylcarbonyloxy grouphaving 1 to 12 carbon atoms,

R^(b11) and R^(b12) may be bonded to each other to form a ring,including —CH—CO— to which R^(b11) and R^(b12) are bonded, and —CH₂—included in the ring may be replaced by —O—, —S— or —CO—,

R^(b13) to R^(b18) each independently represent a halogen atom, ahydroxy group, an aliphatic hydrocarbon group having 1 to 12 carbonatoms, an alkyl fluoride group having 1 to 12 carbon atoms or an alkoxygroup having 1 to 12 carbon atoms,

L^(b31) represents a sulfur atom or an oxygen atom,

o2, p2, s2 and t2 each independently represent an integer of 0 to 5,

q2 and r2 each independently represent an integer of 0 to 4,

u2 represents 0 or 1, and

when o2 is 2 or more, a plurality of R^(b13) are the same or different,when p2 is 2 or more, a plurality of R^(b14) are the same or different,when q2 is 2 or more, a plurality of R^(b15) is are the same ordifferent, when r2 is 2 or more, a plurality of R^(b16) are the same ordifferent, when s2 is 2 or more, a plurality of R^(b17) are the same ordifferent, and when t2 is 2 or more, a plurality of R^(b18) are the sameor different.

When u2 is 0, any one of o2, p2, q2 and r2 is preferably 1 or more, andat least one of R^(b13) to R^(b16) is preferably a halogen atom, andwhen u2 is 1, at least one of o2, p2, s2, t2, q2 and r2 is preferably 1or more, and at least one of R^(b13) to R^(b18) is preferably a halogenatom.

Furthermore, when u2 is 0, r2 is preferably 1 or more, and morepreferably 1. When u2 is 0 and r2 is 1 or more, R^(b16) is preferably ahalogen atom.

The aliphatic hydrocarbon group represents a chain hydrocarbon group andan alicyclic hydrocarbon group.

Examples of the chain hydrocarbon group include alkyl groups such as amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, ahexyl group, an octyl group and a 2-ethylhexyl group.

Particularly, the chain hydrocarbon group of R^(b9) to R^(b12)preferably has 1 to 12 carbon atoms.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,and examples of the monocyclic alicyclic hydrocarbon group includecycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctylgroup and a cyclodecyl group. Examples of the polycyclic alicyclichydrocarbon group include a decahydronaphthyl group, an adamantyl group,a norbornyl group and the following groups.

Particularly, the alicyclic hydrocarbon group of R^(b9) to R^(b12)preferably has 3 to 18 carbon atoms, and more preferably 4 to 12 carbonatoms.

Examples of the alicyclic hydrocarbon group in which a hydrogen atom issubstituted with an aliphatic hydrocarbon group include amethylcyclohexyl group, a dimethylcyclohexyl group, a2-methyladamantan-2-yl group, a 2-ethyladamantan-2-yl group, a2-isopropyladamantan-2-yl group, a methylnorbornyl group, an isobornylgroup and the like. In the alicyclic hydrocarbon group in which ahydrogen atom is substituted with an aliphatic hydrocarbon group, thetotal number of carbon atoms of the alicyclic hydrocarbon group and thealiphatic hydrocarbon group is preferably 20 or less.

The alkyl fluoride group represents an alkyl group having 1 to 12 carbonatoms which has a fluorine atom, and examples thereof include afluoromethyl group, a difluoromethyl group, a trifluoromethyl group, aperfluorobutyl group and the like. The number of carbon atoms of thealkyl fluoride group is preferably 1 to 9, more preferably 1 to 6, stillmore preferably 1 to 4.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a biphenyl group, a naphthyl group and a phenanthrylgroup. The aromatic hydrocarbon group may have a chain hydrocarbon groupor an alicyclic hydrocarbon group, and examples thereof include anaromatic hydrocarbon group which has a chain hydrocarbon group (a tolylgroup, a xylyl group, a cumenyl group, a mesityl group, a p-ethylphenylgroup, a p-tert-butylphenyl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.) and an aromatic hydrocarbon groupwhich has an alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.).

When the aromatic hydrocarbon group has a chain hydrocarbon group or analicyclic hydrocarbon group, a chain hydrocarbon group having 1 to 18carbon atoms and an alicyclic hydrocarbon group having 3 to 18 carbonatoms are preferable.

Examples of the aromatic hydrocarbon group in which a hydrogen atom issubstituted with an alkoxy group include a p-methoxyphenyl group and thelike.

Examples of the chain hydrocarbon group in which a hydrogen atom issubstituted with an aromatic hydrocarbon group include aralkyl groupssuch as a benzyl group, a phenethyl group, a phenylpropyl group, atrityl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkylcarbonyloxy group include a methylcarbonyloxygroup, an ethylcarbonyloxy group, a propylcarbonyloxy group, anisopropylcarbonyloxy group, a butylcarbonyloxy group, asec-butylcarbonyloxy group, a tert-butylcarbonyloxy group, apentylcarbonyloxy group, a hexylcarbonyloxy group, an octylcarbonyloxygroup and a 2-ethylhexylcarbonyloxy group.

The ring formed by bonding R^(b4) and R^(b3) each other, together withsulfur atoms to which R^(b4) and R^(b5) are bonded, may be a monocyclic,polycyclic, aromatic, nonaromatic, saturated or unsaturated ring. Thisring includes a ring having 3 to 18 carbon atoms and is preferably aring having 4 to 18 carbon atoms. The ring containing a sulfur atomincludes a 3-membered to 12-membered ring and is preferably a 3-memberedto 7-membered ring and includes, for example, the following rings andthe like. * represents a bond.

The ring formed by combining R^(b9) and R^(b10) together may be amonocyclic, polycyclic, aromatic, nonaromatic, saturated or unsaturatedring. This ring includes a 3-membered to 12-membered ring and ispreferably a 3-membered to 7-membered ring. The ring includes, forexample, a thiolan-1-ium ring (tetrahydrothiophenium ring), athian-1-ium ring, a 1,4-oxathian-4-ium ring and the like.

The ring formed by combining R^(b11) and R^(b12) together may be amonocyclic, polycyclic, aromatic, nonaromatic, saturated or unsaturatedring. This ring includes a 3-membered to 12-membered ring and ispreferably a 3-membered to 7-membered ring. Examples thereof include anoxocycloheptane ring, an oxocyclohexane ring, an oxonorbornane ring, anoxoadamantane ring and the like.

Of cation (b2-1) to cation (b2-4), a cation (b2-1) is preferable.

Examples of the cation (b2-1) include the following cations.

Examples of the cation (b2-2) include the following cations.

Examples of the cation (b2-3) include the following cations.

Examples of the cation (b2-4) include the following cations.

The salt (I) is a combination of the anion mentioned above and theorganic cation mentioned above, and these can be optionally combined.The salt (I) preferably includes a combination of an anion representedby any one of formula (Ia-1) to formula (Ia-3), formula (Ia-10) toformula (Ia-20), formula (Ia-23) to formula (Ia-25), formula (Ia-31) toformula (Ia-42) with a cation (b2-1), a cation (b2-2), a cation (b2-3)or a cation (b2-4).

Specific examples of the salt (I) include salts shown in Table 1. In thefollowing table, the respective symbols represent symbols imparted tostructures showing the above-mentioned anions and cations. For example,the salt (I-1) means a salt composed of an anion represented by formula(Ia-1) and a cation represented by formula (b2-c-1), and represents thefollowing salt.

TABLE 1 Salt (I) Anion (I) Cation (I) (I-1) (Ia-1) (b2-c-1) (I-2) (Ia-2)(b2-c-1) (I-3) (Ia-3) (b2-c-1) (I-4) (Ia-4) (b2-c-1) (I-5) (Ia-5)(b2-c-1) (I-6) (Ia-6) (b2-c-1) (I-7) (Ia-7) (b2-c-1) (I-8) (Ia-8)(b2-c-1) (I-9) (Ia-9) (b2-c-1) (I-10) (Ia-10) (b2-c-1) (I-11) (Ia-11)(b2-c-1) (I-12) (Ia-12) (b2-c-1) (I-13) (Ia-13) (b2-c-1) (I-14) (Ia-14)(b2-c-1) (I-15) (Ia-15) (b2-c-1) (I-16) (Ia-16) (b2-c-1) (I-17) (Ia-17)(b2-c-1) (I-18) (Ia-18) (b2-c-1) (I-19) (Ia-19) (b2-c-1) (I-20) (Ia-20)(b2-c-1) (I-21) (Ia-21) (b2-c-1) (I-22) (Ia-22) (b2-c-1) (I-23) (Ia-23)(b2-c-1) (I-24) (Ia-24) (b2-c-1) (I-25) (Ia-25) (b2-c-1) (I-26) (Ia-1)(b2-c-10) (I-27) (Ia-2) (b2-c-10) (I-28) (Ia-3) (b2-c-10) (I-29) (Ia-4)(b2-c-10) (I-30) (Ia-5) (b2-c-10) (I-31) (Ia-6) (b2-c-10) (I-32) (Ia-7)(b2-c-10) (I-33) (Ia-8) (b2-c-10) (I-34) (Ia-9) (b2-c-10) (I-35) (Ia-10)(b2-c-10) (I-36) (Ia-11) (b2-c-10) (I-37) (Ia-12) (b2-c-10) (I-38)(Ia-13) (b2-c-10) (I-39) (Ia-14) (b2-c-10) (I-40) (Ia-15) (b2-c-10)(I-41) (Ia-16) (b2-c-10) (I-42) (Ia-17) (b2-c-10) (I-43) (Ia-18)(b2-c-10) (I-44) (Ia-19) (b2-c-10) (I-45) (Ia-20) (b2-c-10) (I-46)(Ia-21) (b2-c-10) (I-47) (Ia-22) (b2-c-10) (I-48) (Ia-23) (b2-c-10)(I-49) (Ia-24) (b2-c-10) (I-50) (Ia-25) (b2-c-10) (I-51) (Ia-1)(b2-c-14) (I-52) (Ia-2) (b2-c-14) (I-53) (Ia-3) (b2-c-14) (I-54) (Ia-4)(b2-c-14) (I-55) (Ia-5) (b2-c-14) (I-56) (Ia-6) (b2-c-14) (I-57) (Ia-7)(b2-c-14) (I-58) (Ia-8) (b2-c-14) (I-59) (Ia-9) (b2-c-14) (I-60) (Ia-10)(b2-c-14) (I-61) (Ia-11) (b2-c-14) (I-62) (Ia-12) (b2-c-14) (I-63)(Ia-13) (b2-c-14) (I-64) (Ia-14) (b2-c-14) (I-65) (Ia-15) (b2-c-14)(I-66) (Ia-16) (b2-c-14) (I-67) (Ia-17) (b2-c-14) (I-68) (Ia-18)(b2-c-14) (I-69) (Ia-19) (b2-c-14) (I-70) (Ia-20) (b2-c-14) (I-71)(Ia-21) (b2-c-14) (I-72) (Ia-22) (b2-c-14) (I-73) (Ia-23) (b2-c-14)(I-74) (Ia-24) (b2-c-14) (I-75) (Ia-25) (b2-c-14) (I-76) (Ia-1)(b2-c-17) (I-77) (Ia-2) (b2-c-17) (I-78) (Ia-3) (b2-c-17) (I-79) (Ia-4)(b2-c-17) (I-80) (Ia-5) (b2-c-17) (I-81) (Ia-6) (b2-c-17) (I-82) (Ia-7)(b2-c-17) (I-83) (Ia-8) (b2-c-17) (I-84) (Ia-9) (b2-c-17) (I-85) (Ia-10)(b2-c-17) (I-86) (Ia-11) (b2-c-17) (I-87) (Ia-12) (b2-c-17) (I-88)(Ia-13) (b2-c-17) (I-89) (Ia-14) (b2-c-17) (I-90) (Ia-15) (b2-c-17)(I-91) (Ia-16) (b2-c-17) (I-92) (Ia-17) (b2-c-17) (I-93) (Ia-18)(b2-c-17) (I-94) (Ia-19) (b2-c-17) (I-95) (Ia-20) (b2-c-17) (I-96)(Ia-21) (b2-c-17) (I-97) (Ia-22) (b2-c-17) (I-98) (Ia-23) (b2-c-17)(I-99) (Ia-24) (b2-c-17) (I-100) (Ia-25) (b2-c-17) (I-101) (Ia-1)(b2-c-18) (I-102) (Ia-2) (b2-c-18) (I-103) (Ia-3) (b2-c-18) (I-104)(Ia-4) (b2-c-18) (I-105) (Ia-5) (b2-c-18) (I-106) (Ia-6) (b2-c-18)(I-107) (Ia-7) (b2-c-18) (I-108) (Ia-8) (b2-c-18) (I-109) (Ia-9)(b2-c-18) (I-110) (Ia-10) (b2-c-18) (I-111) (Ia-11) (b2-c-18) (I-112)(Ia-12) (b2-c-18) (I-113) (Ia-13) (b2-c-18) (I-114) (Ia-14) (b2-c-18)(I-115) (Ia-15) (b2-c-18) (I-116) (Ia-16) (b2-c-18) (I-117) (Ia-17)(b2-c-18) (I-118) (Ia-18) (b2-c-18) (I-119) (Ia-19) (b2-c-18) (I-120)(Ia-20) (b2-c-18) (I-121) (Ia-21) (b2-c-18) (I-122) (Ia-22) (b2-c-18)(I-123) (Ia-23) (b2-c-18) (I-124) (Ia-24) (b2-c-18) (I-125) (Ia-25)(b2-c-18) (I-126) (Ia-1) (b2-c-19) (I-127) (Ia-2) (b2-c-19) (I-128)(Ia-3) (b2-c-19) (I-129) (Ia-4) (b2-c-19) (I-130) (Ia-5) (b2-c-19)(I-131) (Ia-6) (b2-c-19) (I-132) (Ia-7) (b2-c-19) (I-133) (Ia-8)(b2-c-19) (I-134) (Ia-9) (b2-c-19) (I-135) (Ia-10) (b2-c-19) (I-136)(Ia-11) (b2-c-19) (I-137) (Ia-12) (b2-c-19) (I-138) (Ia-13) (b2-c-19)(I-139) (Ia-14) (b2-c-19) (I-140) (Ia-15) (b2-c-19) (I-141) (Ia-16)(b2-c-19) (I-142) (Ia-17) (b2-c-19) (I-143) (Ia-18) (b2-c-19) (I-144)(Ia-19) (b2-c-19) (I-145) (Ia-20) (b2-c-19) (I-146) (Ia-21) (b2-c-19)(I-147) (Ia-22) (b2-c-19) (I-148) (Ia-23) (b2-c-19) (I-149) (Ia-24)(b2-c-19) (I-150) (Ia-25) (b2-c-19) (I-151) (Ia-1) (b2-c-20) (I-152)(Ia-2) (b2-c-20) (I-153) (Ia-3) (b2-c-20) (I-154) (Ia-4) (b2-c-20)(I-155) (Ia-5) (b2-c-20) (I-156) (Ia-6) (b2-c-20) (I-157) (Ia-7)(b2-c-20) (I-158) (Ia-8) (b2-c-20) (I-159) (Ia-9) (b2-c-20) (I-160)(Ia-10) (b2-c-20) (I-161) (Ia-11) (b2-c-20) (I-162) (Ia-12) (b2-c-20)(I-163) (Ia-13) (b2-c-20) (I-164) (Ia-14) (b2-c-20) (I-165) (Ia-15)(b2-c-20) (I-166) (Ia-16) (b2-c-20) (I-167) (Ia-17) (b2-c-20) (I-168)(Ia-18) (b2-c-20) (I-169) (Ia-19) (b2-c-20) (I-170) (Ia-20) (b2-c-20)(I-171) (Ia-21) (b2-c-20) (I-172) (Ia-22) (b2-c-20) (I-173) (Ia-23)(b2-c-20) (I-174) (Ia-24) (b2-c-20) (I-175) (Ia-25) (b2-c-20) (I-176)(Ia-1) (b2-c-27) (I-177) (Ia-2) (b2-c-27) (I-178) (Ia-3) (b2-c-27)(I-179) (Ia-4) (b2-c-27) (I-180) (Ia-5) (b2-c-27) (I-181) (Ia-6)(b2-c-27) (I-182) (Ia-7) (b2-c-27) (I-183) (Ia-8) (b2-c-27) (I-184)(Ia-9) (b2-c-27) (I-185) (Ia-10) (b2-c-27) (I-186) (Ia-11) (b2-c-27)(I-187) (Ia-12) (b2-c-27) (I-188) (Ia-13) (b2-c-27) (I-189) (Ia-14)(b2-c-27) (I-190) (Ia-15) (b2-c-27) (I-191) (Ia-16) (b2-c-27) (I-192)(Ia-17) (b2-c-27) (I-193) (Ia-18) (b2-c-27) (I-194) (Ia-19) (b2-c-27)(I-195) (Ia-20) (b2-c-27) (I-196) (Ia-21) (b2-c-27) (I-197) (Ia-22)(b2-c-27) (I-198) (Ia-23) (b2-c-27) (I-199) (Ia-24) (b2-c-27) (I-200)(Ia-25) (b2-c-27) (I-201) (Ia-1) (b2-c-30) (I-202) (Ia-2) (b2-c-30)(I-203) (Ia-3) (b2-c-30) (I-204) (Ia-4) (b2-c-30) (I-205) (Ia-5)(b2-c-30) (I-206) (Ia-6) (b2-c-30) (I-207) (Ia-7) (b2-c-30) (I-208)(Ia-8) (b2-c-30) (I-209) (Ia-9) (b2-c-30) (I-210) (Ia-10) (b2-c-30)(I-211) (Ia-11) (b2-c-30) (I-212) (Ia-12) (b2-c-30) (I-213) (Ia-13)(b2-c-30) (I-214) (Ia-14) (b2-c-30) (I-215) (Ia-15) (b2-c-30) (I-216)(Ia-16) (b2-c-30) (I-217) (Ia-17) (b2-c-30) (I-218) (Ia-18) (b2-c-30)(I-219) (Ia-19) (b2-c-30) (I-220) (Ia-20) (b2-c-30) (I-221) (Ia-21)(b2-c-30) (I-222) (Ia-22) (b2-c-30) (I-223) (Ia-23) (b2-c-30) (I-224)(Ia-24) (b2-c-30) (I-225) (Ia-25) (b2-c-30) (I-226) (Ia-1) (b2-c-31)(I-227) (Ia-2) (b2-c-31) (I-228) (Ia-3) (b2-c-31) (I-229) (Ia-4)(b2-c-31) (I-230) (Ia-5) (b2-c-31) (I-231) (Ia-6) (b2-c-31) (I-232)(Ia-7) (b2-c-31) (I-233) (Ia-8) (b2-c-31) (I-234) (Ia-9) (b2-c-31)(I-235) (Ia-10) (b2-c-31) (I-236) (Ia-11) (b2-c-31) (I-237) (Ia-12)(b2-c-31) (I-238) (Ia-13) (b2-c-31) (I-239) (Ia-14) (b2-c-31) (I-240)(Ia-15) (b2-c-31) (I-241) (Ia-16) (b2-c-31) (I-242) (Ia-17) (b2-c-31)(I-243) (Ia-18) (b2-c-31) (I-244) (Ia-19) (b2-c-31) (I-245) (Ia-20)(b2-c-31) (I-246) (Ia-21) (b2-c-31) (I-247) (Ia-22) (b2-c-31) (I-248)(Ia-23) (b2-c-31) (I-249) (Ia-24) (b2-c-31) (I-250) (Ia-25) (b2-c-31)(I-251) (Ia-1) (b2-c-28) (I-252) (Ia-2) (b2-c-28) (I-253) (Ia-3)(b2-c-28) (I-254) (Ia-4) (b2-c-28) (I-255) (Ia-5) (b2-c-28) (I-256)(Ia-6) (b2-c-28) (I-257) (Ia-7) (b2-c-28) (I-258) (Ia-8) (b2-c-28)(I-259) (Ia-9) (b2-c-28) (I-260) (Ia-10) (b2-c-28) (I-261) (Ia-11)(b2-c-28) (I-262) (Ia-12) (b2-c-28) (I-263) (Ia-13) (b2-c-28) (I-264)(Ia-14) (b2-c-28) (I-265) (Ia-15) (b2-c-28) (I-266) (Ia-16) (b2-c-28)(I-267) (Ia-17) (b2-c-28) (I-268) (Ia-18) (b2-c-28) (I-269) (Ia-19)(b2-c-28) (I-270) (Ia-20) (b2-c-28) (I-271) (Ia-21) (b2-c-28) (I-272)(Ia-22) (b2-c-28) (I-273) (Ia-23) (b2-c-28) (I-274) (Ia-24) (b2-c-28)(I-275) (Ia-25) (b2-c-28) (I-276) (Ia-26) (b2-c-1) (I-277) (Ia-27)(b2-c-1) (I-278) (Ia-28) (b2-c-1) (I-279) (Ia-29) (b2-c-1) (I-280)(Ia-30) (b2-c-1) (I-281) (Ia-31) (b2-c-1) (I-282) (Ia-32) (b2-c-1)(I-283) (Ia-33) (b2-c-1) (I-284) (Ia-34) (b2-c-1) (I-285) (Ia-35)(b2-c-1) (I-286) (Ia-36) (b2-c-1) (I-287) (Ia-37) (b2-c-1) (I-288)(Ia-38) (b2-c-1) (I-289) (Ia-39) (b2-c-1) (I-290) (Ia-40) (b2-c-1)(I-291) (Ia-41) (b2-c-1) (I-292) (Ia-42) (b2-c-1) (I-293) (Ia-43)(b2-c-1) (I-294) (Ia-44) (b2-c-1) (I-295) (Ia-45) (b2-c-1) (I-296)(Ia-26) (b2-c-10) (I-297) (Ia-27) (b2-c-10) (I-298) (Ia-28) (b2-c-10)(I-299) (Ia-29) (b2-c-10) (I-300) (Ia-30) (b2-c-10) (I-301) (Ia-31)(b2-c-10) (I-302) (Ia-32) (b2-c-10) (I-303) (Ia-33) (b2-c-10) (I-304)(Ia-34) (b2-c-10) (I-305) (Ia-35) (b2-c-10) (I-306) (Ia-36) (b2-c-10)(I-307) (Ia-37) (b2-c-10) (I-308) (Ia-38) (b2-c-10) (I-309) (Ia-39)(b2-c-10) (I-310) (Ia-40) (b2-c-10) (I-311) (Ia-41) (b2-c-10) (I-312)(Ia-42) (b2-c-10) (I-313) (Ia-43) (b2-c-10) (I-314) (Ia-44) (b2-c-10)(I-315) (Ia-45) (b2-c-10) (I-316) (Ia-26) (b2-c-14) (I-317) (Ia-27)(b2-c-14) (I-318) (Ia-28) (b2-c-14) (I-319) (Ia-29) (b2-c-14) (I-320)(Ia-30) (b2-c-14) (I-321) (Ia-31) (b2-c-14) (I-322) (Ia-32) (b2-c-14)(I-323) (Ia-33) (b2-c-14) (I-324) (Ia-34) (b2-c-14) (I-325) (Ia-35)(b2-c-14) (I-326) (Ia-36) (b2-c-14) (I-327) (Ia-37) (b2-c-14) (I-328)(Ia-38) (b2-c-14) (I-329) (Ia-39) (b2-c-14) (I-330) (Ia-40) (b2-c-14)(I-331) (Ia-41) (b2-c-14) (I-332) (Ia-42) (b2-c-14) (I-333) (Ia-43)(b2-c-14) (I-334) (Ia-44) (b2-c-14) (I-335) (Ia-45) (b2-c-14) (I-336)(Ia-26) (b2-c-17) (I-337) (Ia-27) (b2-c-17) (I-338) (Ia-28) (b2-c-17)(I-339) (Ia-29) (b2-c-17) (I-340) (Ia-30) (b2-c-17) (I-341) (Ia-31)(b2-c-17) (I-342) (Ia-32) (b2-c-17) (I-343) (Ia-33) (b2-c-17) (I-344)(Ia-34) (b2-c-17) (I-345) (Ia-35) (b2-c-17) (I-346) (Ia-36) (b2-c-17)(I-347) (Ia-37) (b2-c-17) (I-348) (Ia-38) (b2-c-17) (I-349) (Ia-39)(b2-c-17) (I-350) (Ia-40) (b2-c-17) (I-351) (Ia-41) (b2-c-17) (I-352)(Ia-42) (b2-c-17) (I-353) (Ia-43) (b2-c-17) (I-354) (Ia-44) (b2-c-17)(I-355) (Ia-45) (b2-c-17) (I-356) (Ia-26) (b2-c-18) (I-357) (Ia-27)(b2-c-18) (I-358) (Ia-28) (b2-c-18) (I-359) (Ia-29) (b2-c-18) (I-360)(Ia-30) (b2-c-18) (I-361) (Ia-31) (b2-c-18) (I-362) (Ia-32) (b2-c-18)(I-363) (Ia-33) (b2-c-18) (I-364) (Ia-34) (b2-c-18) (I-365) (Ia-35)(b2-c-18) (I-366) (Ia-36) (b2-c-18) (I-367) (Ia-37) (b2-c-18) (I-368)(Ia-38) (b2-c-18) (I-369) (Ia-39) (b2-c-18) (I-370) (Ia-40) (b2-c-18)(I-371) (Ia-41) (b2-c-18) (I-372) (Ia-42) (b2-c-18) (I-373) (Ia-43)(b2-c-18) (I-374) (Ia-44) (b2-c-18) (I-375) (Ia-45) (b2-c-18) (I-376)(Ia-26) (b2-c-19) (I-377) (Ia-27) (b2-c-19) (I-378) (Ia-28) (b2-c-19)(I-379) (Ia-29) (b2-c-19) (I-380) (Ia-30) (b2-c-19) (I-381) (Ia-31)(b2-c-19) (I-382) (Ia-32) (b2-c-19) (I-383) (Ia-33) (b2-c-19) (I-384)(Ia-34) (b2-c-19) (I-385) (Ia-35) (b2-c-19) (I-386) (Ia-36) (b2-c-19)(I-387) (Ia-37) (b2-c-19) (I-388) (Ia-38) (b2-c-19) (I-389) (Ia-39)(b2-c-19) (I-390) (Ia-40) (b2-c-19) (I-391) (Ia-41) (b2-c-19) (I-392)(Ia-42) (b2-c-19) (I-393) (Ia-43) (b2-c-19) (I-394) (Ia-44) (b2-c-19)(I-395) (Ia-45) (b2-c-19) (I-396) (Ia-26) (b2-c-20) (I-397) (Ia-27)(b2-c-20) (I-398) (Ia-28) (b2-c-20) (I-399) (Ia-29) (b2-c-20) (I-400)(Ia-30) (b2-c-20) (I-401) (Ia-31) (b2-c-20) (I-402) (Ia-32) (b2-c-20)(I-403) (Ia-33) (b2-c-20) (I-404) (Ia-34) (b2-c-20) (I-405) (Ia-35)(b2-c-20) (I-406) (Ia-36) (b2-c-20) (I-407) (Ia-37) (b2-c-20) (I-408)(Ia-38) (b2-c-20) (I-409) (Ia-39) (b2-c-20) (I-410) (Ia-40) (b2-c-20)(I-411) (Ia-41) (b2-c-20) (I-412) (Ia-42) (b2-c-20) (I-413) (Ia-43)(b2-c-20) (I-414) (Ia-44) (b2-c-20) (I-415) (Ia-45) (b2-c-20) (I-416)(Ia-26) (b2-c-27) (I-417) (Ia-27) (b2-c-27) (I-418) (Ia-28) (b2-c-27)(I-419) (Ia-29) (b2-c-27) (I-420) (Ia-30) (b2-c-27) (I-421) (Ia-31)(b2-c-27) (I-422) (Ia-32) (b2-c-27) (I-423) (Ia-33) (b2-c-27) (I-424)(Ia-34) (b2-c-27) (I-425) (Ia-35) (b2-c-27) (I-426) (Ia-36) (b2-c-27)(I-427) (Ia-37) (b2-c-27) (I-428) (Ia-38) (b2-c-27) (I-429) (Ia-39)(b2-c-27) (I-430) (Ia-40) (b2-c-27) (I-431) (Ia-41) (b2-c-27) (I-432)(Ia-42) (b2-c-27) (I-433) (Ia-43) (b2-c-27) (I-434) (Ia-44) (b2-c-27)(I-435) (Ia-45) (b2-c-27) (I-436) (Ia-26) (b2-c-30) (I-437) 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(Ia-55) (b2-c-14) (I-712)(Ia-56) (b2-c-14) (I-713) (Ia-57) (b2-c-14) (I-714) (Ia-58) (b2-c-14)(I-715) (Ia-46) (b2-c-17) (I-716) (Ia-47) (b2-c-17) (I-717) (Ia-48)(b2-c-17) (I-718) (Ia-49) (b2-c-17) (I-719) (Ia-50) (b2-c-17) (I-720)(Ia-51) (b2-c-17) (I-721) (Ia-52) (b2-c-17) (I-722) (Ia-53) (b2-c-17)(I-723) (Ia-54) (b2-c-17) (I-724) (Ia-55) (b2-c-17) (I-725) (Ia-56)(b2-c-17) (I-726) (Ia-57) (b2-c-17) (I-727) (Ia-58) (b2-c-17) (I-728)(Ia-46) (b2-c-18) (I-729) (Ia-47) (b2-c-18) (I-730) (Ia-48) (b2-c-18)(I-731) (Ia-49) (b2-c-18) (I-732) (Ia-50) (b2-c-18) (I-733) (Ia-51)(b2-c-18) (I-734) (Ia-52) (b2-c-18) (I-735) (Ia-53) (b2-c-18) (I-736)(Ia-54) (b2-c-18) (I-737) (Ia-55) (b2-c-18) (I-738) (Ia-56) (b2-c-18)(I-739) (Ia-57) (b2-c-18) (I-740) (Ia-58) (b2-c-18) (I-741) (Ia-46)(b2-c-19) (I-742) (Ia-47) (b2-c-19) (I-743) (Ia-48) (b2-c-19) (I-744)(Ia-49) (b2-c-19) (I-745) (Ia-50) (b2-c-19) (I-746) (Ia-51) (b2-c-19)(I-747) (Ia-52) (b2-c-19) (I-748) (Ia-53) (b2-c-19) (I-749) (Ia-54)(b2-c-19) (I-750) (Ia-55) (b2-c-19) (I-751) (Ia-56) (b2-c-19) (I-752)(Ia-57) (b2-c-19) (I-753) (Ia-58) (b2-c-19) (I-754) (Ia-46) (b2-c-20)(I-755) (Ia-47) (b2-c-20) (I-756) (Ia-48) (b2-c-20) (I-757) (Ia-49)(b2-c-20) (I-758) (Ia-50) (b2-c-20) (I-759) (Ia-51) (b2-c-20) (I-760)(Ia-52) (b2-c-20) (I-761) (Ia-53) (b2-c-20) (I-762) (Ia-54) (b2-c-20)(I-763) (Ia-55) (b2-c-20) (I-764) (Ia-56) (b2-c-20) (I-765) (Ia-57)(b2-c-20) (I-766) (Ia-58) (b2-c-20) (I-767) (Ia-46) (b2-c-27) (I-768)(Ia-47) (b2-c-27) (I-769) (Ia-48) (b2-c-27) (I-770) (Ia-49) (b2-c-27)(I-771) (Ia-50) (b2-c-27) (I-772) (Ia-51) (b2-c-27) (I-773) (Ia-52)(b2-c-27) (I-774) (Ia-53) (b2-c-27) (I-775) (Ia-54) (b2-c-27) (I-776)(Ia-55) (b2-c-27) (I-777) (Ia-56) (b2-c-27) (I-778) (Ia-57) (b2-c-27)(I-779) (Ia-58) (b2-c-27) (I-780) (Ia-46) (b2-c-30) (I-781) (Ia-47)(b2-c-30) (I-782) (Ia-48) (b2-c-30) (I-783) (Ia-49) (b2-c-30) (I-784)(Ia-50) (b2-c-30) (I-785) (Ia-51) (b2-c-30) (I-786) (Ia-52) (b2-c-30)(I-787) (Ia-53) (b2-c-30) (I-788) (Ia-54) (b2-c-30) (I-789) (Ia-55)(b2-c-30) (I-790) (Ia-56) (b2-c-30) (I-791) (Ia-57) (b2-c-30) (I-792)(Ia-58) (b2-c-30) (I-793) (Ia-46) (b2-c-31) (I-794) (Ia-47) (b2-c-31)(I-795) (Ia-48) (b2-c-31) (I-796) (Ia-49) (b2-c-31) (I-797) (Ia-50)(b2-c-31) (I-798) (Ia-51) (b2-c-31) (I-799) (Ia-52) (b2-c-31) (I-800)(Ia-53) (b2-c-31) (I-801) (Ia-54) (b2-c-31) (I-802) (Ia-55) (b2-c-31)(I-803) (Ia-56) (b2-c-31) (I-804) (Ia-57) (b2-c-31) (I-805) (Ia-58)(b2-c-31) (I-806) (Ia-46) (b2-c-28) (I-807) (Ia-47) (b2-c-28) (I-808)(Ia-48) (b2-c-28) (I-809) (Ia-49) (b2-c-28) (I-810) (Ia-50) (b2-c-28)(I-811) (Ia-51) (b2-c-28) (I-812) (Ia-52) (b2-c-28) (I-813) (Ia-53)(b2-c-28) (I-814) (Ia-54) (b2-c-28) (I-815) (Ia-55) (b2-c-28) (I-816)(Ia-56) (b2-c-28) (I-817) (Ia-57) (b2-c-28) (I-818) (Ia-58) (b2-c-28)(I-819) (Ia-46) (b2-c-47) (I-820) (Ia-47) (b2-c-47) (I-821) (Ia-48)(b2-c-47) (I-822) (Ia-49) (b2-c-47) (I-823) (Ia-50) (b2-c-47) (I-824)(Ia-51) (b2-c-47) (I-825) (Ia-52) (b2-c-47) (I-826) (Ia-53) (b2-c-47)(I-827) (Ia-54) (b2-c-47) (I-828) (Ia-55) (b2-c-47) (I-829) (Ia-56)(b2-c-47) (I-830) (Ia-57) (b2-c-47) (I-831) (Ia-58) (b2-c-47) (I-832)(Ia-46) (b2-c-48) (I-833) (Ia-47) (b2-c-48) (I-834) (Ia-48) (b2-c-48)(I-835) (Ia-49) (b2-c-48) (I-836) (Ia-50) (b2-c-48) (I-837) (Ia-51)(b2-c-48) (I-838) (Ia-52) (b2-c-48) (I-839) (Ia-53) (b2-c-48) (I-840)(Ia-54) (b2-c-48) (I-841) (Ia-55) (b2-c-48) (I-842) (Ia-56) (b2-c-48)(I-843) (Ia-57) (b2-c-48) (I-844) (Ia-58) (b2-c-48) (I-845) (Ia-46)(b2-c-51) (I-846) (Ia-47) (b2-c-51) (I-847) (Ia-48) (b2-c-51) (I-848)(Ia-49) (b2-c-51) (I-849) (Ia-50) (b2-c-51) (I-850) (Ia-51) (b2-c-51)(I-851) (Ia-52) (b2-c-51) (I-852) (Ia-53) (b2-c-51) (I-853) (Ia-54)(b2-c-51) (I-854) (Ia-55) (b2-c-51) (I-855) (Ia-56) (b2-c-51) (I-856)(Ia-57) (b2-c-51) (I-857) (Ia-58) (b2-c-51) (I-858) (Ia-46) (b2-c-54)(I-859) (Ia-47) (b2-c-54) (I-860) (Ia-48) (b2-c-54) (I-861) (Ia-49)(b2-c-54) (I-862) (Ia-50) (b2-c-54) (I-863) (Ia-51) (b2-c-54) (I-864)(Ia-52) (b2-c-54) (I-865) (Ia-53) (b2-c-54) (I-866) (Ia-54) (b2-c-54)(I-867) (Ia-55) (b2-c-54) (I-868) (Ia-56) (b2-c-54) (I-869) (Ia-57)(b2-c-54) (I-870) (Ia-58) (b2-c-54)

Of these, the salt (I) is preferably salt (I-1) to salt (I-3), salt(I-10) to salt (I-20), salt (I-23) to salt (I-28), salt (I-35) to salt(I-45), salt (I-48) to salt (I-53), salt (I-60) to salt (I-70), salt(I-73) to salt (I-78), salt (I-85) to salt (I-95), salt (I-98) to salt(I-103), salt (I-110) to salt (I-120), salt (I-123) to salt (I-128),salt (I-135) to salt (I-145), salt (I-148) to salt (I-153), salt (I-160)to salt (I-170), salt (I-173) to salt (I-178), salt (I-185) to salt(I-195), salt (I-198) to salt (I-203), salt (I-210) to salt (I-220),salt (I-223) to salt (I-228), salt (I-235) to salt (I-245), salt (I-248)to salt (I-253), salt (I-260) to salt (I-270), salt (I-273) to salt(I-275), salt (I-281) to salt (I-292), salt (I-301) to salt (I-312),salt (I-321) to salt (I-332), salt (I-341) to salt (I-352), salt (I-361)to salt (I-372), salt (I-381) to salt (I-392), salt (I-401) to salt(I-412), salt (I-421) to salt (I-432), salt (I-441) to salt (I-452),salt (I-461) to salt (I-472), salt (I-481) to salt (I-492), salt (I-496)to salt (I-498), salt (I-505) to salt (I-515), salt (I-518) to salt(I-520), salt (I-526) to salt (I-537), salt (I-541) to salt (I-543),salt (I-550) to salt (I-560), salt (I-563) to salt (I-565), salt (I-571)to salt (I-583), salt (I-586) to salt (I-588), salt (I-595) to salt(I-605), salt (I-608) to salt (I-610), salt (I-616) to salt (I-627),salt (I-631) to salt (I-633), salt (I-640) to salt (I-650), salt (I-653)to salt (I-655) or salt (I-661) to salt (I-672).

<Method for Producing Salt (I)>

A salt in which X⁰ is *—CO—O— (* represents a bonding site to C(R¹¹)(R¹²) or C(Q¹) (Q²) in the salt (I) (salt represented by formula (I1))can be produced, for example, by reacting a salt represented by formula(I1-a) with carbonyldiimidazole in a solvent, followed by furtherreaction with a compound represented by formula (I1-b):

wherein all symbols are the same as defined above.

Examples of the solvent in this reaction include chloroform,acetonitrile and the like.

The reaction temperature is usually 5° C. to 80° C., and the reactiontime is usually 0.5 hour to 24 hours.

The salt represented by formula (I1-a) includes, for example, a saltrepresented by the following and can be produced by the method mentionedin JP 2008-127367 A.

The compound represented by formula (I1-b) includes compoundsrepresented by the following formulas and is easily available on themarket and also can be easily produced by a known production method.

A salt in which X⁰ is *—O—CO—O— in the salt (I) (salt represented byformula (I2)) can be produced, for example, by reacting a saltrepresented by formula (I2-a) with carbonyldiimidazole in a solvent,followed by a reaction with a compound represented by formula (I1-b).

The salt represented by formula (I2) can also be produced, for example,by reacting a compound represented by formula (I1-b) withcarbonyldiimidazole in a solvent, followed by a reaction with a saltrepresented by formula (I2-a):

wherein all symbols are the same as defined above.

Examples of the solvent in this reaction include chloroform,acetonitrile and the like.

The reaction temperature is usually 5° C. to 80° C., and the reactiontime is usually 0.5 hour to 24 hours.

The salt represented by formula (I2-a) includes, for example, a saltrepresented by the following, and can be produced by the methodmentioned in JP 2012-193170 A.

A salt in which X⁰ is *—O—CO— in the salt (I) (salt represented byformula (I3)) can be produced, for example, by reacting a compoundrepresented by formula (I3-b) with carbonyldiimidazole in a solvent,followed by a reaction with a salt represented by formula (I2-a):

wherein all symbols are the same as defined above. Examples of thesolvent in this reaction include chloroform, acetonitrile and the like.

The reaction temperature is usually 5° C. to 80° C., and the reactiontime is usually 0.5 hour to 24 hours.

The compound represented by formula (I3-b) includes, for example,compounds represented by the following formulas, which are easilyavailable on the market and also can be easily produced by a knownmethod.

A salt in which X⁰ is *—O— in the salt (I) (salt represented by formula(I4)) can be obtained by reacting a salt represented by formula (I2-a)with a compound represented by formula (I1-b) in the presence of a basein a solvent:

wherein all symbols are the same as defined above.

Examples of the base in this reaction include potassium hydroxide andthe like.

Examples of the solvent in this reaction include acetonitrile and thelike.

The reaction temperature is usually 5° C. to 80° C., and the reactiontime is usually 0.5 hour to 24 hours.

It is possible to produce a salt in which L1 is a group obtained bycombining an alkanediyl group having 1 to 4 carbon atoms with analicyclic hydrocarbon group having 3 to 18 carbon atoms (in which —CH₂—included the alkanediyl group may be replaced by —O— or —CO—, and —CH₂—included in the alicyclic hydrocarbon group may be replaced by —O—, —S—,—SO₂— or —CO—) in the salt (I) by replacing a salt represented byformula (I1-a) or a salt represented by formula (I2-a) in the case ofsynthesizing salts represented by formula (I1) to formula (I4) by saltsrepresented by the followings.

<Acid Generator>

The acid generator of the present invention is an acid generatorcomprising the salt (I). The salt (I) may be included alone, or two ormore thereof may be included in combination.

The acid generator of the present invention may comprise, in addition tothe salt (I), an acid generator known in the resist field (hereinaftersometimes referred to as “acid generator (B)”). The acid generator (B)may be used alone, or two or more acid generators may be used incombination.

Either nonionic or ionic acid generator may be used as the acidgenerator (B). Examples of the nonionic acid generator include sulfonateesters (e.g., 2-nitrobenzyl ester, aromatic sulfonate, oxime sulfonate,N-sulfonyloxyimide, sulfonyloxyketone, diazonaphthoquinone 4-sulfonate),sulfones (e.g., disulfone, ketosulfone, sulfonyldiazomethane) and thelike. Typical examples of the ionic acid generator include onium saltscontaining an onium cation (e.g., diazonium salt, phosphonium salt,sulfonium salt, iodonium salt). Examples of the anion of the onium saltinclude sulfonic acid anion, sulfonylimide anion, sulfonylmethide anionand the like.

Specific examples of the acid generator (B) include compounds generatingan acid upon exposure to radiation mentioned in JP 63-26653 A, JP55-164824 A, JP 62-69263 A, JP 63-146038 A, JP 63-163452 A, JP 62-153853A, JP 63-146029 A, U.S. Pat. Nos. 3,779,778, 3,849,137, DE Pat. No.3914407 and EP Patent No. 126,712. Compounds produced by a known methodmay also be used. Two or more acid generators (B) may also be used incombination.

The acid generator (B) is preferably a fluorine-containing acidgenerator, and more preferably a salt represented by formula (B1)(hereinafter sometimes referred to as “acid generator (B1)”.

wherein, in formula (B1),

Q^(b1) and Q^(b2) each independently represent a fluorine atom or aperfluoroalkyl group having 1 to 6 carbon atoms,

L^(b1) represents a divalent saturated hydrocarbon group having 1 to 24carbon atoms, —CH₂— included in the saturated hydrocarbon group may bereplaced by —O— or —CO—, and a hydrogen atom included in the saturatedhydrocarbon group may be substituted with a fluorine atom or a hydroxygroup,

Y represents a methyl group which may have a substituent or an alicyclichydrocarbon group having 3 to 24 carbon atoms which may have asubstituent, and —CH₂— included in the alicyclic hydrocarbon group maybe replaced by —O—, —SO₂— or —CO—, and

Z1⁺ represents an organic cation.

Examples of the perfluoroalkyl group represented by Q^(b1) and Q^(b2)include a trifluoromethyl group, a perfluoroethyl group, aperfluoropropyl group, a perfluoroisopropyl group, a perfluorobutylgroup, a perfluorosec-butyl group, a perfluorotert-butyl group, aperfluoropentyl group and a perfluorohexyl group.

Preferably, Q^(b1) and Q^(b2) are each independently a fluorine atom ora trifluoromethyl group, and more preferably, both are fluorine atoms.

Examples of the divalent saturated hydrocarbon group in L^(b1) include alinear alkanediyl group, a branched alkanediyl group, a monocyclic orpolycyclic divalent alicyclic saturated hydrocarbon group, or thedivalent saturated hydrocarbon group may be a group formed by combiningtwo or more of these groups.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a heptane-1,7-diyl group, an octane-1,8-diyl group, anonane-1,9-diyl group, a decane-1,10-diyl group, an undecane-1,11-diylgroup, a dodecane-1,12-diyl group, a tridecane-1,13-diyl group, atetradecane-1,14-diyl group, a pentadecane-1,15-diyl group, ahexadecane-1,16-diyl group and a heptadecane-1,17-diyl group;

branched alkanediyl groups such as an ethane-1,1-diyl group, apropane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diylgroup, a pentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group;

monocyclic divalent alicyclic saturated hydrocarbon groups such as acyclobutane-1,3-diyl group, a cyclopentane-1,3-diyl group, acyclohexane-1,4-diyl group and a cyclooctane-1,5-diyl group; and

polycyclic divalent alicyclic saturated hydrocarbon groups such as anorbornane-1,4-diyl group, a norbornane-2,5-diyl group, anadamantane-1,5-diyl group and an adamantane-2,6-diyl group.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L^(b1) is replaced by —O— or —CO— includes, forexample, a group represented by any one of formula (b1-1) to formula(b1-3). In groups represented by formula (b1-1) to formula (b1-3) andgroups represented by formula (b1-4) to formula (b1-11) which arespecific examples thereof, * and ** represent a bonding site, and *represents a bonding site to —Y.

In formula (b1-1),

L^(b2) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 22 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom,

L^(b3) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 22 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group, and —CH₂— included in the saturated hydrocarbon group maybe replaced by —O— or —CO—, and

the total number of carbon atoms of L^(b2) and L^(b3) is 22 or less.

In formula (b1-2),

L^(b4) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 22 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom,

L^(b5) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 22 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group, and —CH₂— included in the saturated hydrocarbon group maybe replaced by —O— or —CO—, and

the total number of carbon atoms of L^(b4) and L^(b5) is 22 or less.

In formula (b1-3),

L^(b6) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 23 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group,

L^(b7) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 23 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group, and —CH₂— included in the saturated hydrocarbon group maybe replaced by —O— or —CO—, and

the total number of carbon atoms of L^(b6) and L^(b7) is 23 or less.

In groups represented by formula (b1-1) to formula (b1-3), when —CH₂—included in the saturated hydrocarbon group is replaced by —O— or —CO—,the number of carbon atoms before replacement is taken as the number ofcarbon atoms of the saturated hydrocarbon group.

Examples of the divalent saturated hydrocarbon group include those whichare the same as the divalent saturated hydrocarbon group of L^(b1).

L^(b2) is preferably a single bond.

L^(b3) is preferably a divalent saturated hydrocarbon group having 1 to4 carbon atoms.

L^(b4) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms, and a hydrogen atom included in the divalent saturatedhydrocarbon group may be substituted with a fluorine atom.

L^(b3) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 8 carbon atoms.

L^(b6) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 4 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom.

L^(b7) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group, and —CH₂— included in the divalent saturated hydrocarbongroup may be replaced by —O— or —CO—.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L^(b1) is replaced by —O— or —CO— is preferably agroup represented by formula (b1-1) or formula (b1-3).

Examples of the group represented by formula (b1-1) include groupsrepresented by formula (b1-4) to formula (b1-8).

In formula (b1-4),

L^(b8) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 22 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom or ahydroxy group.

In formula (b1-5),

L^(b9) represents a divalent saturated hydrocarbon group having 1 to 20carbon atoms, and —CH₂— included in the divalent saturated hydrocarbongroup may be replaced by —O— or —CO—.

L^(b10) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 19 carbon atoms, and a hydrogen atom included in thedivalent saturated hydrocarbon group may be substituted with a fluorineatom or a hydroxy group, and the total number of carbon atoms of L^(b9)and L^(b10) is 20 or less.

In formula (b1-6),

L^(b11) represents a divalent saturated hydrocarbon group having 1 to 21carbon atoms,

L^(b12) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 20 carbon atoms, and a hydrogen atom included in thedivalent saturated hydrocarbon group may be substituted with a fluorineatom or a hydroxy group, and the total number of carbon atoms of L^(b1)and L^(b12) is 21 or less.

In formula (b1-7),

L^(b13) represents a divalent saturated hydrocarbon group having 1 to 19carbon atoms,

L^(b14) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, and —CH₂— included in the divalentsaturated hydrocarbon group may be replaced by —O— or —CO—,

L^(b15) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, and a hydrogen atom included in thedivalent saturated hydrocarbon group may be substituted with a fluorineatom or a hydroxy group, and

the total number of carbon atoms of L^(b13) to L^(b15) is 19 or less.

In formula (b1-8),

L^(b16) represents a divalent saturated hydrocarbon group having 1 to 18carbon atoms, and —CH₂— included in the divalent saturated hydrocarbongroup may be replaced by —O— or —CO—,

L^(b17) represents a divalent saturated hydrocarbon group having 1 to 18carbon atoms,

L^(b18) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 17 carbon atoms, and a hydrogen atom included in thedivalent saturated hydrocarbon group may be substituted with a fluorineatom or a hydroxy group, and

the total number of carbon atoms of L^(b16) to L^(b18) is 19 or less.

L^(b8) is preferably a divalent saturated hydrocarbon group having 1 to4 carbon atoms.

L^(b9) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms.

L^(b10) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 19 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 8 carbon atoms.

L^(b11) is preferably a divalent saturated hydrocarbon group having 1 to8 carbon atoms.

L^(b12) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 8 carbon atoms.

L^(b13) is preferably a divalent saturated hydrocarbon group having 1 to12 carbon atoms.

L^(b14) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 6 carbon atoms.

L^(b15) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 18 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 8 carbon atoms.

L^(b16) is preferably a divalent saturated hydrocarbon group having 1 to12 carbon atoms.

L^(b17) is preferably a divalent saturated hydrocarbon group having 1 to6 carbon atoms.

L^(b18) is preferably a single bond or a divalent saturated hydrocarbongroup having 1 to 17 carbon atoms, and more preferably a single bond ora divalent saturated hydrocarbon group having 1 to 4 carbon atoms.

Examples of the group represented by formula (b1-3) include groupsrepresented by formula (b1-9) to formula (b1-11).

In formula (b1-9),

L^(b19) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 23 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom,

L^(b20) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 23 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom, ahydroxy group or an alkylcarbonyloxy group, —CH₂— included in thealkylcarbonyloxy group may be replaced by —O— or —CO—, and a hydrogenatom included in the alkylcarbonyloxy group may be substituted with ahydroxy group, and

the total number of carbon atoms of L^(b19) and L^(b20) is 23 or less.

In formula (b1-10),

L^(b21) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 21 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom,

L^(b22) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 21 carbon atoms,

L^(b23) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 21 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom, ahydroxy group or an alkylcarbonyloxy group, —CH₂— included in thealkylcarbonyloxy group may be replaced by —O— or —CO—, and a hydrogenatom included in the alkylcarbonyloxy group may be substituted with ahydroxy group, and

the total number of carbon atoms of L^(b21), L^(b22) and L^(b23) is 21or less.

In formula (b1-11),

L^(b24) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 20 carbon atoms, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom,

L^(b25) represents a divalent saturated hydrocarbon group having 1 to 21carbon atoms,

L^(b26) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 20 carbon atoms, a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a fluorine atom, ahydroxy group or an alkylcarbonyloxy group, —CH₂— included in thealkylcarbonyloxy group may be replaced by —O— or —CO—, and a hydrogenatom included in the alkylcarbonyloxy group may be substituted with ahydroxy group, and

the total number of carbon atoms of L^(b24), L^(b23) and L^(b26) is 21or less.

In the group represented by formula (b1-9) to the group represented byformula (b1-11), when a hydrogen atom included in the saturatedhydrocarbon group is substituted with an alkylcarbonyloxy group, thenumber of carbon atoms before substitution is taken as the number ofcarbon atoms of the saturated hydrocarbon group.

Examples of the alkylcarbonyloxy group include an acetyloxy group, apropionyloxy group, a butyryloxy group, a cyclohexylcarbonyloxy group,an adamantylcarbonyloxy group and the like.

Examples of the group represented by formula (b1-4) include thefollowings:

Examples of the group represented by formula (b1-5) include thefollowings:

Examples of the group represented by formula (b1-6) include thefollowings:

Examples of the group represented by formula (b1-7) include thefollowings:

Examples of the group represented by formula (b1-8) include thefollowings:

Examples of the group represented by formula (b1-2) include thefollowings:

Examples of the group represented by formula (b1-9) include thefollowings:

Examples of the group represented by formula (b1-10) include thefollowings:

Examples of the group represented by formula (b1-11) include thefollowings:

Examples of the alicyclic hydrocarbon group represented by Y includegroups represented by formula (Y1) to formula (Y11) and formula (Y36) toformula (Y38).

When —CH₂— included in the alicyclic hydrocarbon group represented by Yis replaced by —O—, —S(O)₂— or —CO—, the number may be 1, or 2 or more.Examples of such group include groups represented by formula (Y12) toformula (Y35) and formula (Y39) to formula (Y43). * represents a bondingsite to L^(b1).

The alicyclic hydrocarbon group represented by Y is preferably a grouprepresented by any one of formula (Y1) to formula (Y20), formula (Y26),formula (Y27), formula (Y30), formula (Y31) and formula (Y39) to formula(Y43), more preferably a group represented by formula (Y11), formula(Y15), formula (Y16), formula (Y20), formula (Y26), formula (Y27),formula (Y30), formula (Y31), formula (Y39), formula (Y40), formula(Y42) or formula (Y43), and still more preferably a group represented byformula (Y11), formula (Y15), formula (Y20), formula (Y26), formula(Y27), formula (Y30), formula (Y31), formula (Y39), formula (Y40),formula (Y42) or formula (Y43).

When the alicyclic hydrocarbon group represented by Y is a spiro ringhaving an oxygen atom, such as formula (Y28) to formula (Y35), formula(Y39), formula (Y40), formula (Y42) or formula (Y43), the alkanediylgroup between two oxygen atoms preferably has one or more fluorineatoms. Of alkanediyl groups included in a ketal structure, it ispreferable that a methylene group adjacent to the oxygen atom is notsubstituted with a fluorine atom.

Examples of the substituent of the methyl group represented by Y includea halogen atom, a hydroxy group, an alicyclic hydrocarbon group having 3to 16 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, a glycidyloxy group, a —(CH₂)_(ja)—CO—O—R^(b1) group or a—(CH₂)_(ja)—O—CO—R^(b1) group (wherein R^(b1) represents an alkyl grouphaving 1 to 16 carbon atoms, an alicyclic hydrocarbon group having 3 to16 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, or a group obtained by combining these groups, ja represents aninteger of 0 to 4, —CH₂— included in the alkyl group and the alicyclichydrocarbon group may be replaced by —O—, —SO₂— or —CO—, and a hydrogenatom included in the alkyl group, the alicyclic hydrocarbon group andthe aromatic hydrocarbon group may be substituted with a hydroxy groupor a fluorine atom).

Examples of the substituent of the alicyclic hydrocarbon grouprepresented by Y include a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 16 carbon atoms which may be substituted with a hydroxygroup (—CH₂— included in the alkyl group may be replaced by —O— or—CO—), an alicyclic hydrocarbon group having 3 to 16 carbon atoms, anaromatic hydrocarbon group having 6 to 18 carbon atoms, an aralkyl grouphaving 7 to 21 carbon atoms, a glycidyloxy group, a—(CH₂)_(ja)—CO—O—R^(b1) group or a —(CH₂)_(ja)—O—CO—R^(b1) group(wherein R^(b1) represents an alkyl group having 1 to 16 carbon atoms,an alicyclic hydrocarbon group having 3 to 16 carbon atoms, an aromatichydrocarbon group having 6 to 18 carbon atoms or a group obtained bycombining these groups, ja represents an integer of 0 to 4, —CH₂—included in the alkyl group and the alicyclic hydrocarbon group may bereplaced by —O—, —SO₂— or —CO—, and a hydrogen atom included in thealkyl group, the alicyclic hydrocarbon group and the aromatichydrocarbon group may be substituted with a hydroxy group or a fluorineatom).

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alicyclic hydrocarbon group include a cyclopentyl group,a cyclohexyl group, a methylcyclohexyl group, a dimethylcyclohexylgroup, a cycloheptyl group, a cyclooctyl group, a norbornyl group, anadamantyl group and the like. The alicyclic hydrocarbon group may have achain hydrocarbon group, and examples thereof include a methylcyclohexylgroup, a dimethylcyclohexyl group and the like. The number of carbonatoms of the alicyclic hydrocarbon group is preferably 3 to 12, and morepreferably 3 to 10.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group. The aromatic hydrocarbon group may have a chainhydrocarbon group or an alicyclic hydrocarbon group, and examples of thearomatic hydrocarbon group which has a chain hydrocarbon group include atolyl group, a xylyl group, a cumenyl group, a mesityl group, ap-ethylphenyl group, a p-tert-butylphenyl group, a 2,6-diethylphenylgroup, a 2-methyl-6-ethylphenyl group and the like, and examples of thearomatic hydrocarbon group which has an alicyclic hydrocarbon groupinclude a p-cyclohexylphenyl group, a p-adamantylphenyl group and thelike. The number of carbon atoms of the aromatic hydrocarbon group ispreferably 6 to 14, and more preferably 6 to 10.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, a heptyl group, a2-ethylhexyl group, an octyl group, a nonyl group, a decyl group, anundecyl group, a dodecyl group and the like. The number of carbon atomsof the alkyl group is preferably 1 to 12, more preferably 1 to 6, andstill more preferably 1 to 4.

Examples of the alkyl group substituted with a hydroxy group includehydroxyalkyl groups such as a hydroxymethyl group and a hydroxyethylgroup.

Examples of the aralkyl group include a benzyl group, a phenethyl group,a phenylpropyl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the group in which —CH₂— included in the alkyl group isreplaced by —O—, —SO₂— or —CO— include an alkoxy group, an alkylsulfonylgroup, an alkoxycarbonyl group, an alkylcarbonyl group, analkylcarbonyloxy group, or a group obtained by combining these groups.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup. The number of carbon atoms of the alkoxy group is preferably 1 to12, more preferably 1 to 6, and still more preferably 1 to 4.

Examples of the alkylsulfonyl group include a methylsulfonyl group, anethylsulfonyl group, a propylsulfonyl group and the like. The number ofcarbon atoms of the alkylsulfonyl group is preferably 1 to 12, morepreferably 1 to 6, and still more preferably 1 to 4.

Examples of the alkoxycarbonyl group include a methoxycarbonyl group, anethoxycarbonyl group, a butoxycarbonyl group and the like. The number ofcarbon atoms of the alkoxycarbonyl group is preferably 2 to 12, morepreferably 2 to 6, and still more preferably 2 to 4.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group. The number of carbon atoms of thealkylcarbonyl group is preferably 2 to 12, more preferably 2 to 6, andstill more preferably 2 to 4.

Examples of the alkylcarbonyloxy group include an acetyloxy group, apropionyloxy group, a butyryloxy group and the like. The number ofcarbon atoms of the alkylcarbonyloxy group is preferably 2 to 12, morepreferably 2 to 6, and still more preferably 2 to 4.

Examples of the combined group include a group obtained by combining analkoxy group with an alkyl group, a group obtained by combining analkoxy group with an alkoxy group, a group obtained by combining analkoxy group with an alkylcarbonyl group, a group obtained by combiningan alkoxy group with an alkylcarbonyloxy group and the like.

Examples of the group obtained by combining an alkoxy group with analkyl group include alkoxyalkyl groups such as a methoxymethyl group, amethoxyethyl group, an ethoxyethyl group, an ethoxymethyl group and thelike. The number of carbon atoms of the alkoxyalkyl group is preferably2 to 12, more preferably 2 to 6, and still more preferably 2 to 4.

Examples of the group obtained by combining an alkoxy group with analkoxy group include alkoxyalkoxy groups such as a methoxymethoxy group,a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxy group andthe like. The number of carbon atoms of the alkoxyalkoxy group ispreferably 2 to 12, more preferably 2 to 6, and still more preferably 2to 4.

Examples of the group obtained by combining an alkoxy group with analkylcarbonyl group include alkoxyalkylcarbonyl groups such as amethoxyacetyl group, a methoxypropionyl group, an ethoxyacetyl group, anethoxypropionyl group and the like. The number of carbon atoms of thealkoxyalkylcarbonyl group is preferably 3 to 13, more preferably 3 to 7,and still more preferably 3 to 5.

Examples of the group obtained by combining an alkoxy group with analkylcarbonyloxy group include alkoxyalkylcarbonyloxy groups such as amethoxyacetyloxy group, a methoxypropionyloxy group, an ethoxyacetyloxygroup, an ethoxypropionyloxy group and the like. The number of carbonatoms of the alkoxyalkylcarbonyloxy group is preferably 3 to 13, morepreferably 3 to 7, and still more preferably 3 to 5.

Examples of the group in which —CH₂— included in the alicyclichydrocarbon group is replaced by —O—, —SO₂— or —CO— include groupsrepresented by formula (Y12) to formula (Y35), formula (Y39) to formula(Y43) and the like.

Examples of Y include the followings.

Y is preferably an alicyclic hydrocarbon group having 3 to 24 carbonatoms which may have a substituent, more preferably an alicyclichydrocarbon group having 3 to 20 carbon atoms which may have asubstituent, still more preferably an alicyclic hydrocarbon group having3 to 18 carbon atoms which may have a substituent, yet more preferablyan adamantyl group which may have a substituent, and —CH₂— constitutingthe alicyclic hydrocarbon group or the adamantyl group may be replacedby —CO—, —SO₂— or —CO—. Specifically, Y is preferably an adamantylgroup, a hydroxyadamantyl group, an oxoadamantyl group, or groupsrepresented by formula (Y42) and formula (Y100) to formula (Y114).

The anion in the salt represented by formula (B1) is preferably anionsrepresented by formula (B1-A-1) to formula (B1-A-59) [hereinaftersometimes referred to as “anion (B1-A-1)” according to the number offormula], and more preferably an anion represented by any one of formula(B1-A-1) to formula (B1-A-4), formula (B1-A-9), formula (B1-A-10),formula (B1-A-24) to formula (B1-A-33), formula (B1-A-36) to formula(B1-A-40) and formula (B1-A-47) to formula (B1-A-59).

R¹² to R¹⁷ independently represent, for example, an alkyl group having 1to 4 carbon atoms, and preferably a methyl group or an ethyl group. R¹⁸is, for example, a chain hydrocarbon group having 1 to 12 carbon atoms,preferably an alkyl group having 1 to 4 carbon atoms, an alicyclichydrocarbon group having 5 to 12 carbon atoms, or groups formed bycombining these groups, and more preferably a methyl group, an ethylgroup, a cyclohexyl group or an adamantyl group. L^(A41) is a singlebond or an alkanediyl group having 1 to 4 carbon atoms. Q^(b1) andQ^(b2) are the same as defined above.

Specific examples of the anion in the salt represented by formula (B1)include anions mentioned in JP 2010-204646 A.

Preferable anions represented by formula (B1) are anions represented byformula (B1a-1) to formula (B1a-38).

Of these, an anion represented by any one of formula (B1a-1) to formula(B1a-3), formula (B1a-7) to formula (B1a-16), formula (B1a-18), formula(B1a-19) and formula (B1a-22) to formula (B1a-38) is preferable.

Examples of the organic cation as for Z1+ include an organic oniumcation, an organic sulfonium cation, an organic iodonium cation, anorganic ammonium cation, a benzothiazolium cation and an organicphosphonium cation. Of these, an organic sulfonium cation and an organiciodonium cation are preferable, and an arylsulfonium cation is morepreferable. Examples of the arylsulfonium cation include those which arethe same as the cation as for Z⁺ in formula (I).

The acid generator (B) is a combination of the anion mentioned above andthe organic cation mentioned above, and these can be optionallycombined. The acid generator (B) preferably includes a combination of ananion represented by any one of formula (B1a-1) to formula (B1a-3),formula (B1a-7) to formula (B1a-16), formula (B1a-18), formula (B1a-19)and formula (B1a-22) to formula (B1a-38) with a cation (b2-1), a cation(b2-3) or a cation (b2-4).

The acid generator (B) preferably includes those represented by formula(B1-1) to formula (B1-57). Of these acid generators, those containing anarylsulfonium cation are preferable and those represented by formula(B1-1) to formula (B1-3), formula (B1-5) to formula (B1-7), formula(B1-11) to formula (B1-14), formula (B1-20) to formula (B1-26), formula(B1-29) and formula (B1-31) to formula (B1-57) are particularlypreferable.

When the salt (I) and the acid generator (B) are included as the acidgenerator, a ratio of the content of the salt (I) and that of the acidgenerator (B) (mass ratio; salt (I):acid generator (B)) is usually 1:99to 99:1, preferably 2:98 to 98:2, more preferably 5:95 to 95:5, stillmore preferably 10:90 to 90:10, and particularly preferably 15:85 to85:15.

<Resist Composition>

The resist composition of the present invention comprises an acidgenerator comprising a salt (I) and a resin having an acid-labile group(hereinafter sometimes referred to as “resin (A)”). The “acid-labilegroup” means a group having a leaving group which is eliminated bycontact with an acid, thus converting a constitutional unit into aconstitutional unit having a hydrophilic group (e.g. a hydroxy group ora carboxy group).

The resist composition of the present invention preferably comprises aquencher such as a salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator (hereinafter sometimesreferred to as “quencher (C)”), and preferably comprises a solvent(hereinafter sometimes referred to as “solvent (E)”).

<Acid Generator>

In the resist composition of the present invention, the total content ofthe acid generator is preferably 1 part by mass or more and 45 parts bymass or less, more preferably 1 part by mass or more and 40 parts bymass or less, still more preferably 3 parts by mass or more and 40 partsby mass or less, yet more preferably 3 parts by mass or more and 35parts by mass or less, and further preferably 5 parts by mass or moreand 35 parts by mass or less, based on 100 parts by mass of thebelow-mentioned resin (A).

<Resin (A)>

The resin (A) includes a structural unit having an acid-labile group(hereinafter sometimes referred to as “structural unit (a1)”). It ispreferable that the resin (A) further includes a structural unit otherthan the structural unit (a1). Examples of the structural unit otherthan the structural unit (a1) include a structural unit having noacid-labile group (hereinafter sometimes referred to as “structural unit(s)”), a structural unit other than the structural unit (a1) and thestructural unit (s) (e.g. a structural unit having a halogen atommentioned later (hereinafter sometimes referred to as “structural unit(a4)”), a structural unit having a non-leaving hydrocarbon groupmentioned later (hereinafter sometimes referred to as “structural unit(a5)”) and other structural units derived from monomers known in theart.

<Structural Unit (a1)>

The structural unit (a1) is derived from a monomer having an acid-labilegroup (hereinafter sometimes referred to as “monomer (a1)”).

The acid-labile group contained in the resin (A) is preferably a grouprepresented by formula (1) (hereinafter also referred to as group (1))and/or a group represented by formula (2) (hereinafter also referred toas group (2)):

wherein, in formula (1), R^(a1), R^(a2) and R^(a3) each independentlyrepresent an alkyl group having 1 to 8 carbon atoms, an alkenyl grouphaving 2 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to20 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, or a group obtained by combining these groups, or R^(a1) andR^(a2) are bonded to each other to form a non-aromatic hydrocarbon ringhaving 3 to 20 carbon atoms together with carbon atoms to which R^(a1)and R^(a2) are bonded,

ma and na each independently represent 0 or 1, and at least one of maand na represents 1, and

* represents a bonding site:

wherein, in formula (2), R^(a1)′ and R^(a2)′ each independentlyrepresent a hydrogen atom or a hydrocarbon group having 1 to 12 carbonatoms, R^(a3)′ represents a hydrocarbon group having 1 to 20 carbonatoms, or R^(a2)′ and R^(a3)′ are bonded to each other to form aheterocyclic ring having 3 to 20 carbon atoms together with carbon atomsand X to which R^(a2)′ and R^(a3)′ are bonded, and —CH₂— included in thehydrocarbon group and the heterocyclic ring may be replaced by —O— or—S—,

X represents an oxygen atom or a sulfur atom,

na′ represents 0 or 1, and

* represents a bonding site.

Examples of the alkyl group in R^(a1), R^(a2) and R^(a3) include amethyl group, an ethyl group, a propyl group, a butyl group, a pentylgroup, a hexyl group, a heptyl group, an octyl group and the like.

Examples of the alkenyl group in R^(a1), R^(a2) and R^(a3) include anethenyl group, a propenyl group, an isopropenyl group, a butenyl group,an isobutenyl group, a tert-butenyl group, a pentenyl group, a hexenylgroup, a heptenyl group, an octenyl group, an isooctenyl group, anonenyl group and the like.

The alicyclic hydrocarbon group in R^(a1), R^(a2) and R^(a3) may beeither monocyclic or polycyclic. Examples of the monocyclic alicyclichydrocarbon group include cycloalkyl groups such as a cyclopentyl group,a cyclohexyl group, a cycloheptyl group and a cyclooctyl group. Examplesof the polycyclic alicyclic hydrocarbon group include adecahydronaphthyl group, an adamantyl group, a norbornyl group and thefollowing groups (* represents a bonding site). The number of carbonatoms of the alicyclic hydrocarbon group of R^(a1), R^(a2) and R^(a3) ispreferably 3 to 16.

Examples of the aromatic hydrocarbon group in R^(a1), R^(a2) and R^(a3)include aryl groups such as a phenyl group, a naphthyl group, an anthrylgroup, a biphenyl group and a phenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

Preferably, ma is 0 and na is 1.

When R^(a1) and R^(a2) are bonded to each other to form a non-aromatichydrocarbon ring, examples of —C(R^(a1)) (R^(a2)) (R^(a3)) include thefollowing rings. The non-aromatic hydrocarbon ring preferably has 3 to12 carbon atoms. * represents a bonding site to —O—.

Examples of the hydrocarbon group in R^(a1)′, R^(a2)′ and R^(a3)′include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups formed by combining these groups.

Examples of the alkyl group and the alicyclic hydrocarbon group includethose which are the same as mentioned in R^(a1), R^(a2) and R^(a3).

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group, and the like.

When R^(a2)′ and R^(a3)′ are bonded to each other to form a heterocyclicring together with carbon atoms and X to which R^(a2)′ and R^(a3)′ arebonded, examples of —C(R^(a1)′) (R^(a2)′)—X—R^(a3)′ include thefollowing rings. * represents a bonding site.

At least one of R^(a1)′ and R^(a2)′ is preferably a hydrogen atom.

na′ is preferably 0.

Examples of the group (1) include the following groups.

A group wherein, in formula (1), R^(a1), R^(a2) and R^(a3) are alkylgroups, ma=0 and na=1. The group is preferably a tert-butoxycarbonylgroup.

A group wherein, in formula (1), R^(a1) and R^(a2) are bonded to eachother to form an adamantyl group together with carbon atoms to whichR^(a1) and R^(a2) are bonded, R^(a3) is an alkyl group, ma=0 and na=1.

A group wherein, in formula (1), R^(a1) and R^(a2) are eachindependently an alkyl group, R^(a3) is an adamantyl group, ma=0 andna=1.

Specific examples of the group (1) include the following groups. *represents a bonding site.

Specific examples of the group (2) include the following groups. *represents a bonding site.

The monomer (a1) is preferably a monomer having an acid-labile group andan ethylenic unsaturated bond, and more preferably a (meth)acrylicmonomer having an acid-labile group.

Of the (meth)acrylic monomers having an acid-labile group, those havingan alicyclic hydrocarbon group having 5 to 20 carbon atoms arepreferably exemplified. When a resin (A) including a structural unitderived from a monomer (a1) having a bulky structure such as analicyclic hydrocarbon group is used in a resist composition, it ispossible to improve the resolution of a resist pattern.

Examples of the structural unit derived from a (meth)acrylic monomerhaving a group (1) include a structural unit represented by formula(a1-C) (hereinafter sometimes referred to as structural unit (a1-0)), astructural unit represented by formula (a1-1) (hereinafter sometimesreferred to as structural unit (a1-1)) or a structural unit representedby formula (a1-2) (hereinafter sometimes referred to as structural unit(a1-2)). The structural unit is preferably at least one structural unitselected from the group consisting of a structural unit (a1-0), astructural unit (a1-1) and a structural unit (a1-2), and more preferablyat least one structural unit selected from the group consisting of astructural unit (a1-1) and a structural unit (a1-2). These structuralunits may be used alone, or two or more structural units may be used incombination.

In formula (a1-0), formula (a1-1) and formula (a1-2),

L^(a01), L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *represents a bonding site to —CO—,

R^(a01), R^(a4) and R^(a5) each independently represent a hydrogen atom,a halogen atom, or an alkyl group having 1 to 6 carbon atoms which mayhave a halogen atom,

R^(a02), R^(a03) and R^(a04) each independently represent an alkyl grouphaving 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to18 carbon atoms, an aromatic hydrocarbon group having 6 to 18 carbonatoms, or a group obtained by combining these groups,

R^(a6) and R^(a7) each independently represent an alkyl group having 1to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, analicyclic hydrocarbon group having 3 to 18 carbon atoms, an aromatichydrocarbon group having 6 to 18 carbon atoms, or a group obtained bycombining these groups,

m1 represents an integer of 0 to 14,

n1 represents an integer of 0 to 10, and

n1′ represents an integer of 0 to 3.

R^(a01), R^(a4) and R^(a5) are preferably a hydrogen atom or a methylgroup, and more preferably a methyl group.

L^(a01), L^(a1) and L^(a2) are preferably an oxygen atom or*—O—(CH₂)_(k01)—CO—O— (in which k01 is preferably an integer of 1 to 4,and more preferably 1), and more preferably an oxygen atom.

Examples of the alkyl group, the alicyclic hydrocarbon group, thearomatic hydrocarbon group, and the group obtained by combining thesegroups in R^(a02), R^(a03) and R^(a04) include groups which are the sameas mentioned in R^(a1), R^(a2) and R^(a3) of the group (1).

Examples of the alkyl group, the alkenyl group, the alicyclichydrocarbon group, the aromatic hydrocarbon group, and groups obtainedby combining these groups in R^(a6) and R^(a7) include the same groupsas mentioned for R^(a1), R^(a2) and R^(a3) of formula (1).

The alkyl group in R^(a02), R^(a03) and R^(a04) is preferably an alkylgroup having 1 to 6 carbon atoms, more preferably a methyl group or anethyl group, and still more preferably a methyl group.

The alkyl group in R^(a6) and R^(a7) is preferably an alkyl group having1 to 6 carbon atoms, more preferably a methyl group, an ethyl group, anisopropyl group or a t-butyl group, and still more preferably an ethylgroup, an isopropyl group or a t-butyl group.

The alkenyl group in R^(a6) and R^(a7) is preferably an alkenyl grouphaving 2 to 6 carbon atoms, and more preferably an ethenyl group, apropenyl group, an isopropenyl group or a butenyl group.

The number of carbon atoms of the alicyclic hydrocarbon group as forR^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) is preferably 5 to 12, andmore preferably 5 to 10.

The number of carbon atoms of the aromatic hydrocarbon group as forR^(a02), R^(a03), R^(a04), R^(a6) and R^(a7) is preferably 6 to 12, andmore preferably 6 to 10.

The total number of carbon atoms of the group obtained by combining thealkyl group with the alicyclic hydrocarbon group is preferably 18 orless.

The total number of carbon atoms of the group obtained by combining thealkyl group with the aromatic hydrocarbon group is preferably 18 orless.

R^(a02) and R^(a03) are preferably an alkyl group having 1 to 6 carbonatoms or an aromatic hydrocarbon group having 6 to 12 carbon atoms, andmore preferably a methyl group, an ethyl group, a phenyl group or anaphthyl group.

R^(a04) is preferably an alkyl group having 1 to 6 carbon atoms or analicyclic hydrocarbon group having 5 to 12 carbon atoms, and morepreferably a methyl group, an ethyl group, a cyclohexyl group or anadamantyl group.

Preferably, R^(a6) and R^(a7) are each independently an alkyl grouphaving 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atomsor an aromatic hydrocarbon group having 6 to 12 carbon atoms, morepreferably a methyl group, an ethyl group, an isopropyl group, a t-butylgroup, an ethenyl group, a phenyl group or a naphthyl group, and stillmore preferably an ethyl group, an isopropyl group, a t-butyl group, anethenyl group or a phenyl group.

m1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

n1′ is preferably 0 or 1.

The structural unit (a1-0) includes, for example, a structural unitrepresented by any one of formula (a1-0-1) to formula (a1-0-18) and astructural unit in which a methyl group corresponding to R^(a01) in thestructural unit (a1-0) is substituted with a hydrogen atom, a halogenatom, a haloalkyl group or other alkyl groups and is preferably astructural unit represented by any one of formula (a1-0-1) to formula(a1-0-10), formula (a1-0-13) and formula (a1-0-14).

The structural unit (a1-1) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. Of thesestructural units, a structural unit represented by any one of formula(a1-1-1) to formula (a1-1-7) and a structural unit in which a methylgroup corresponding to R^(a4) in the structural unit (a1-1) issubstituted with a hydrogen atom, a halogen atom, a haloalkyl group orother alkyl groups are preferable, and a structural unit represented byany one of formula (a1-1-1) to formula (a1-1-4) is more preferable.

Examples of the structural unit (a1-2) include a structural unitrepresented by any one of formula (a1-2-1) to formula (a1-2-14) and astructural unit in which a methyl group corresponding to R^(a5) in thestructural unit (a1-2) is substituted with a hydrogen atom, a halogenatom, a haloalkyl group or other alkyl groups, and a structure unitrepresented by any one of formula (a1-2-2), formula (a1-2-5), formula(a1-2-6) and formula (a1-2-10) to formula (a1-2-14) is preferable.

When the resin (A) includes a structural unit (a1-0), the contentthereof is usually 5 to 80 mol %, preferably 5 to 75 mol %, and morepreferably 10 to 70 mol %, based on all structural units of the resin(A).

When the resin (A) includes a structural unit (a1-1) and/or a structuralunit (a1-2), the total content thereof is usually 10 to 90 mol %,preferably 15 to 85 mol %, more preferably 20 to 80 mol %, still morepreferably 20 to 75 mol %, and yet more preferably 20 to 70 mol %, basedon all structural units of the resin (A).

In the structural unit (a1), examples of the structural unit having agroup (2) include a structural unit represented by formula (a1-4)(hereinafter sometimes referred to as “structural unit (a1-4)”):

wherein, in formula (a1-4),

R^(a32) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom,

R^(a33) represents a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,an alkoxyalkyl group having 2 to 12 carbon atoms, an alkoxyalkoxy grouphaving 2 to 12 carbon atoms, an alkylcarbonyl group having 2 to 4 carbonatoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, anacryloyloxy group or a methacryloyloxy group,

A^(a30) represents a single bond or *—X^(a31)-(A^(a32)-X^(a32)) and *represents a bonding site to carbon atoms to which —R^(a32) is bonded,

A^(a32) represents an alkanediyl group having 1 to 6 carbon atoms,

X^(a31) and X^(a32) each independently represent —O—, —CO—O— or —O—CO—,

nc represents 0 or 1,

la represents an integer of 0 to 4, and when la is an integer of 2 ormore, a plurality of R^(a33) may be the same or different from eachother, and

R^(a34) and R^(a35) each independently represent a hydrogen atom or ahydrocarbon group having 1 to 12 carbon atoms, R^(a36) represents ahydrocarbon group having 1 to 20 carbon atoms, or R^(a35) and R^(a36)are bonded to each other to form a divalent hydrocarbon group having 2to 20 carbon atoms together with —C—O— to which R^(a35) and R^(a36) arebonded, and —CH₂— included in the hydrocarbon group and the divalenthydrocarbon group may be replaced by —O— or —S—.

Examples of the halogen atom in R^(a32) and R^(a33) include a fluorineatom, a chlorine atom and a bromine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom in R^(a32) include a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl groupand a perfluorohexyl group.

R^(a32) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the alkyl group in R^(a33) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group. The alkylgroup is preferably an alkyl group having 1 to 4 carbon atoms, morepreferably a methyl group or an ethyl group, and still more preferably amethyl group.

Examples of the alkoxy group in R^(a33) include a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, asec-butoxy group, a tert-butoxy group, a pentyloxy group and a hexyloxygroup. The alkoxy group is preferably an alkoxy group having 1 to 4carbon atoms, more preferably a methoxy group or an ethoxy group, andstill more preferably a methoxy group.

Examples of the alkoxyalkyl group in R^(a33) include a methoxymethylgroup, an ethoxyethyl group, a propoxymethyl group, an isopropoxymethylgroup, a butoxymethyl group, a sec-butoxymethyl group and atert-butoxymethyl group. The alkoxyalkyl group is preferably analkoxyalkyl group having 2 to 8 carbon atoms, more preferably amethoxymethyl group or an ethoxyethyl group, and still more preferably amethoxymethyl group.

Examples of the alkoxyalkoxy group in R^(a33) include a methoxymethoxygroup, a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxygroup, a propoxymethoxy group, an isopropoxymethoxy group, abutoxymethoxy group, a sec-butoxymethoxy group and a tert-butoxymethoxygroup. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having2 to 8 carbon atoms, and more preferably a methoxyethoxy group or anethoxyethoxy group.

Examples of the alkylcarbonyl group in R^(a33) include an acetyl group,a propionyl group and a butyryl group. The alkylcarbonyl group ispreferably an alkylcarbonyl group having 2 to 3 carbon atoms, and morepreferably an acetyl group.

Examples of the alkylcarbonyloxy group in R^(a33) include an acetyloxygroup, a propionyloxy group and a butyryloxy group. The alkylcarbonyloxygroup is preferably an alkylcarbonyloxy group having 2 to 3 carbonatoms, and more preferably an acetyloxy group.

R^(a33) is preferably a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atomsor an alkoxyalkoxy group having 2 to 8 carbon atoms, more preferably afluorine atom, an iodine atom, a hydroxy group, a methyl group, amethoxy group, an ethoxy group, an ethoxyethoxy group or anethoxymethoxy group, and still more preferably a fluorine atom, aniodine atom, a hydroxy group, a methyl group, a methoxy group or anethoxyethoxy group.

Examples of the *—X^(a31)-(A^(a32)-X^(a32))_(nc)— include *—O—, *—CO—O—,*—O—CO—, *—CO—O-A^(a32)-CO—O—, *—O—CO-A^(a32)-O—, *—O-A^(a32)-CO—O—,*—CO—O-A^(a32)-O—CO— and *—O—CO-A^(a32)-O—CO. Of these, *—CO—O—,*—CO—O-A^(a32)-CO—O— or *—O-A^(a32)-CO—O— is preferable.

Examples of the alkanediyl group in A^(a32) include a methylene group,an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a butane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

A^(a32) is preferably a methylene group or an ethylene group.

A^(a30) is preferably a single bond, *—CO—O— or *—CO—O-A^(a32)-CO—O—,more preferably a single bond, *—CO—O— or *—CO—O—CH₂—CO—O—, and stillmore preferably a single bond or *—CO—O—.

la is preferably 0, 1 or 2, more preferably 0 or 1, and still morepreferably 0.

Examples of the hydrocarbon group in R^(a34), R^(a35) and R^(a36)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups formed by combining these groups.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, a butyl group, a pentyl group, a hexyl group, a heptylgroup, an octyl group and the like.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic.Examples of the monocyclic alicyclic hydrocarbon group includecycloalkyl groups such as a cyclopentyl group, a cyclohexyl group, acycloheptyl group and a cyclooctyl group. Examples of the polycyclicalicyclic hydrocarbon group include a decahydronaphthyl group, anadamantyl group, a norbornyl group and the following groups (*represents a bonding site).

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group (e.g.,alkylcycloalkyl groups or cycloalkylalkyl groups, such as amethylcyclohexyl group, a dimethylcyclohexyl group, a methylnorbornylgroup, a cyclohexylmethyl group, an adamantylmethyl group, anadamantyldimethyl group and a norbornylethyl group), aralkyl groups suchas a benzyl group, aromatic hydrocarbon groups having an alkyl group (ap-methylphenyl group, a p-tert-butylphenyl group, a tolyl group, a xylylgroup, a cumenyl group, a mesityl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl group, etc.), aromatic hydrocarbon groups havingan alicyclic hydrocarbon group (a p-cyclohexylphenyl group, ap-adamantylphenyl group, etc.), aryl-cycloalkyl groups such as aphenylcyclohexyl group and the like. Particularly, examples of R^(a36)include an alkyl group having 1 to 18 carbon atoms, an alicyclichydrocarbon group having 3 to 18 carbon atoms, an aromatic hydrocarbongroup having 6 to 18 carbon atoms, or a group formed by combining thesegroups.

R^(a34) is preferably a hydrogen atom.

R^(a35) is preferably a hydrogen atom, an alkyl group having 1 to 12carbon atoms or an alicyclic hydrocarbon group having 3 to 12 carbonatoms, and more preferably a methyl group or an ethyl group.

The hydrocarbon group of R^(a36) is preferably an alkyl group having 1to 18 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbonatoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or agroup formed by combining these groups, and more preferably an alkylgroup having 1 to 18 carbon atoms, an alicyclic hydrocarbon group having3 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms.The alkyl group and the alicyclic hydrocarbon group in R^(a36) arepreferably unsubstituted. The aromatic hydrocarbon group in R^(a36) ispreferably an aromatic ring having an aryloxy group having 6 to 10carbon atoms.

—OC(R^(a34)) (R^(a33))—O—R^(a36) in the structural unit (a1-4) iseliminated by contacting with an acid (e.g., p-toluenesulfonic acid) toform a hydroxy group.

—OC(R^(a34)) (R^(a33))—O—R^(a36) is preferably bonded to the o-positionor the p-position of the benzene ring, and more preferably thep-position.

The structural unit (a1-4) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. The structuralunit preferably includes structural units represented by formula(a1-4-1) to formula (a1-4-24) and a structural unit in which a hydrogenatom corresponding to R^(a32) in the structural unit (a1-4) issubstituted with a halogen atom, a haloalkyl group or an alkyl group,and more preferably structural units represented by formula (a1-4-1) toformula (a1-4-5), formula (a1-4-10), formula (a1-4-13) and formula(a1-4-14).

When the resin (A) includes the structural unit (a1-4), the content ispreferably 3 to 80 mol %, more preferably 5 to 75 mol %, still morepreferably 7 to 70 mol %, yet more preferably 7 to 65 mol %, andparticularly preferably 10 to 60 mol %, based on the total of allstructural units of the resin (A).

The structural unit derived from a (meth)acrylic monomer having a group(2) also includes a structural unit represented by formula (a1-5)(hereinafter sometimes referred to as “structural unit (a1-5)”).

In formula (a1-5),

R^(a8) represents an alkyl group having 1 to 6 carbon atoms which mayhave a halogen atom, a hydrogen atom or a halogen atom,

Z^(a1) represents a single bond or *—(CH₂)_(h3)—CO-L⁵⁴-, h3 representsan integer of 1 to 4, and * represents a bonding site to L⁵¹,

L⁵¹, L⁵², L⁵³ and L⁵⁴ each independently represent —O— or —S—,

s1 represents an integer of 1 to 3, and

s1′ represents an integer of 0 to 3.

The halogen atom includes a fluorine atom and a chlorine atom and ispreferably a fluorine atom. Examples of the alkyl group having 1 to 6carbon atoms which may have a halogen atom include a methyl group, anethyl group, a propyl group, a butyl group, a pentyl group, a hexylgroup, a heptyl group, an octyl group, a fluoromethyl group and atrifluoromethyl group.

In formula (a1-5), R^(a8) is preferably a hydrogen atom, a methyl groupor a trifluoromethyl group,

L⁵¹ is preferably an oxygen atom,

one of L⁵² and L⁵³ is preferably —O— and the other one is preferably—S—,

s1 is preferably 1,

s1′ is preferably an integer of 0 to 2, and

Z^(a1) is preferably a single bond or *—CH₂—CO—O—.

The structural unit (a1-5) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-61117 A. Of thesestructural units, structural units represented by formula (a1-5-1) toformula (a1-5-4) are preferable, and structural units represented byformula (a1-5-1) or formula (a1-5-2) are more preferable.

When the resin (A) includes the structural unit (a1-5), the content ispreferably 1 to 50 mol %, more preferably 3 to 45 mol %, still morepreferably 5 to 40 mol %, and yet more preferably 5 to 30 mol %, basedon all structural units of the resin (A).

The structural unit (a1) also includes the following structural units.

When the resin (A) includes the above-mentioned structural units such as(a1-3-1) to (a1-3-7), the content is preferably 10 to 95 mol %, morepreferably 15 to 90 mol %, still more preferably 20 to 85 mol %, yetmore preferably 20 to 70 mol %, and particularly preferably 20 to 60 mol%, based on all structural units of the resin (A).

The structural unit (a1) also includes the following structural units.

When the resin (A) includes structural units such as (a1-6-1) to(a1-6-3) mentioned above, the content is preferably 10 to 60 mol %, morepreferably 15 to 55 mol %, still more preferably 20 to 50 mol %, yetmore preferably 20 to 45 mol %, and particularly preferably 20 to 40 mol%, based on all structural units of the resin (A).

<Structural Unit (s)>

The structural unit (s) is derived from a monomer having no acid-labilegroup (hereinafter sometimes referred to as “monomer (s)”). It ispossible to use, as the monomer from which the structural unit (s) isderived, a monomer having no acid-labile group known in the resistfield.

The structural unit (s) preferably has a hydroxy group or a lactonering. When a resin including a structural unit having a hydroxy groupand having no acid-labile group (hereinafter sometimes referred to as“structural unit (a2)”) and/or a structural unit having a lactone ringand having no acid-labile group (hereinafter sometimes referred to as“structural unit (a3)”) is used in the resist composition of the presentinvention, it is possible to improve the resolution of a resist patternand the adhesion to a substrate.

<Structural Unit (a2)>

The hydroxy group possessed by the structural unit (a2) may be either analcoholic hydroxy group or a phenolic hydroxy group.

When a resist pattern is produced from the resist composition of thepresent invention, in the case of using, as an exposure source, highenergy rays such as KrF excimer laser (248 nm), electron beam or extremeultraviolet light (EUV), a structural unit (a2) having a phenolichydroxy group is preferably used, and the below-mentioned structuralunit (a2-A) is more preferably used, as the structural unit (a2). Whenusing ArF excimer laser (193 nm) or the like, a structural unit (a2)having an alcoholic hydroxy group is preferably used, and thebelow-mentioned structural unit (a2-1) is more preferably used, as thestructural unit (a2). The structural unit (a2) may be included alone, ortwo or more structural units may be included.

In the structural unit (a2), examples of the structural unit having aphenolic hydroxy group include a structural unit represented by formula(a2-A) (hereinafter sometimes referred to as “structural unit (a2-A)”).

wherein, in formula (a2-A),

R^(a30) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom,

R^(a51) represents a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,an alkoxyalkyl group having 2 to 12 carbon atoms, an alkoxyalkoxy grouphaving 2 to 12 carbon atoms, an alkylcarbonyl group having 2 to 4 carbonatoms, an alkylcarbonyloxy group having 2 to 4 carbon atoms, anacryloyloxy group or a methacryloyloxy group,

A^(a50) represents a single bond or *—X^(a)s1-(A^(a52)-X^(a)s2)_(nb)—and * represents a bonding site to carbon atoms to which —R^(a50) isbonded,

A^(a52) represents an alkanediyl group having 1 to 6 carbon atoms,

X^(a51) and X^(a52) each independently represent —O—, —CO—O— or —O—CO—,

nb represents 0 or 1, and

mb represents an integer of 0 to 4, and when mb is an integer of 2 ormore, a plurality of R^(a51) may be the same or different from eachother.

Examples of the halogen atom in R^(a50) and R^(a51) include a fluorineatom, a chlorine atom and a bromine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom in R^(a50) include a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl groupand a perfluorohexyl group.

R^(a50) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the alkyl group in R^(a51) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group. The alkylgroup is preferably an alkyl group having 1 to 4 carbon atoms, morepreferably a methyl group or an ethyl group, and still more preferably amethyl group.

Examples of the alkoxy group in R^(a51) include a methoxy group, anethoxy group, a propoxy group, an isopropoxy group, a butoxy group, asec-butoxy group and a tert-butoxy group. The alkoxy group is preferablyan alkoxy group having 1 to 4 carbon atoms, more preferably a methoxygroup or an ethoxy group, and still more preferably a methoxy group.

Examples of the alkoxyalkyl group in R^(a51) include a methoxymethylgroup, an ethoxyethyl group, a propoxymethyl group, an isopropoxymethylgroup, a butoxymethyl group, a sec-butoxymethyl group and atert-butoxymethyl group. The alkoxyalkyl group is preferably analkoxyalkyl group having 2 to 8 carbon atoms, more preferably amethoxymethyl group or an ethoxyethyl group, and still more preferably amethoxymethyl group.

Examples of the alkoxyalkoxy group in R^(a51) include a methoxymethoxygroup, a methoxyethoxy group, an ethoxymethoxy group, an ethoxyethoxygroup, a propoxymethoxy group, an isopropoxymethoxy group, abutoxymethoxy group, a sec-butoxymethoxy group and a tert-butoxymethoxygroup. The alkoxyalkoxy group is preferably an alkoxyalkoxy group having2 to 8 carbon atoms, and more preferably a methoxyethoxy group or anethoxyethoxy group.

Examples of the alkylcarbonyl group in R^(a51) include an acetyl group,a propionyl group and a butyryl group. The alkylcarbonyl group ispreferably an alkylcarbonyl group having 2 to 3 carbon atoms, and morepreferably an acetyl group.

Examples of the alkylcarbonyloxy group in R^(a51) include an acetyloxygroup, a propionyloxy group and a butyryloxy group. The alkylcarbonyloxygroup is preferably an alkylcarbonyloxy group having 2 to 3 carbonatoms, and more preferably an acetyloxy group.

R^(a51) is preferably a halogen atom, a hydroxy group, an alkyl grouphaving 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atomsor an alkoxyalkoxy group having 2 to 8 carbon atoms, more preferably afluorine atom, an iodine atom, a hydroxy group, a methyl group, amethoxy group, an ethoxy group, an ethoxyethoxy group or anethoxymethoxy group, and still more preferably a fluorine atom, aniodine atom, a hydroxy group, a methyl group, a methoxy group or anethoxyethoxy group.

Examples of *—X^(a51)-(A^(a52)-X^(a52))_(nb)— include *—O—, *—CO—O—,*—O—CO—, *—CO—O-A^(a52)-CO—O—, *—O—CO-A^(a52)-O—, *—O-A^(a52)-CO—O—,*—CO—O-A^(a52)-O—CO— and *—O—CO-A^(a2)-O—CO—. Of these, *—CO—O—,*—CO—O-A^(a52)-CO—O— or *—O-A^(a52)-CO—O— is preferable.

Examples of the alkanediyl group in A^(a52) include a methylene group,an ethylene group, a propane-1,3-diyl group, a propane-1,2-diyl group, abutane-1,4-diyl group, a pentane-1,5-diyl group, a hexane-1,6-diylgroup, a butane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

A^(a52) is preferably a methylene group or an ethylene group.

A^(a50) is preferably a single bond, *—CO—O— or *—CO—O-A^(a52)-CO—O—,more preferably a single bond, *—CO—O— or *—CO—O—CH₂—CO—O—, and stillmore preferably a single bond or *—CO—O—.

mb is preferably 0, 1 or 2, more preferably 0 or 1, and still morepreferably 0.

The hydroxy group is preferably bonded to the o-position or thep-position of a benzene ring, and more preferably the p-position.

Examples of the structural unit (a2-A) include structural units derivedfrom the monomers mentioned in JP 2010-204634 A and JP 2012-12577 A.

Examples of the structural unit (a2-A) include structural unitsrepresented by formula (a2-2-1) to formula (a2-2-24), and a structuralunit in which a methyl group corresponding to R^(a50) in the structuralunit (a2-A) is substituted with a hydrogen atom, a halogen atom, ahaloalkyl group or other alkyl groups in structural units represented byformula (a2-2-1) to formula (a2-2-24). The structural unit (a2-A) ispreferably a structural unit represented by formula (a2-2-1), astructural unit represented by formula (a2-2-3), a structural unitrepresented by formula (a2-2-6), a structural unit represented byformula (a2-2-8), structural units represented by formula (a2-2-12) toformula (a2-2-14), and structural units in which a methyl groupcorresponding to R^(a50) in the structural unit (a2-A) is substitutedwith a hydrogen atom in a structural unit represented by formula(a2-2-1), a structural unit represented by formula (a2-2-3), astructural unit represented by formula (a2-2-6), a structural unitrepresented by formula (a2-2-8) and structural units represented byformula (a2-2-12) to formula (a2-2-14), more preferably a structuralunit represented by formula (a2-2-3), a structural unit represented byformula (a2-2-8), structural units represented by formula (a2-2-12) toformula (a2-2-14), and structural units in which a methyl groupcorresponding to R^(a50) in the structural unit (a2-A) is substitutedwith a hydrogen atom in a structural unit represented by formula(a2-2-3) or a structural unit represented by formula (a2-2-8) andstructural units represented by formula (a2-2-12) to formula (a2-2-14),and still more preferably a structural unit represented by formula(a2-2-8) and a structural unit in which a methyl group corresponding toR^(a50) in the structural unit (a2-A) is substituted with a hydrogenatom in a structural unit represented by formula (a2-2-8).

When the structural unit (a2-A) is included in the resin (A), thecontent of the structural unit (a2-A) is preferably 5 to 80 mol %, morepreferably 10 to 70 mol %, still more preferably 15 to 65 mol %, and yetmore preferably 20 to 65 mol %, based on all structural units.

The structural unit (a2-A) can be included in a resin (A) bypolymerizing, for example, with a structural unit (a1-4) and treatingwith an acid such as p-toluenesulfonic acid. The structural unit (a2-A)can also be included in the resin (A) by polymerizing withacetoxystyrene and treating with an alkali such as tetramethylammoniumhydroxide.

Examples of the structural unit having an alcoholic hydroxy group in thestructural unit (a2) include a structural unit represented by formula(a2-1) (hereinafter sometimes referred to as “structural unit (a2-1)”).

In formula (a2-1),

L^(a3) represents —O— or *—O—(CH₂)_(k2)—CO—O—,

k2 represents an integer of 1 to 7, and * represents a bonding site to—CO—,

R^(a14) represents a hydrogen atom or a methyl group,

R^(a15) and R^(a16) each independently represent a hydrogen atom, amethyl group or a hydroxy group, and

o1 represents an integer of 0 to 10.

In formula (a2-1), L^(a3) is preferably —O— or —O—(CH₂)_(f1)—CO—O— (f1represents an integer of 1 to 4), and more preferably —O—,

R^(a14) is preferably a methyl group,

R^(a15) is preferably a hydrogen atom,

R^(a16) is preferably a hydrogen atom or a hydroxy group, and

o1 is preferably an integer of 0 to 3, and more preferably 0 or 1.

The structural unit (a2-1) includes, for example, structural unitsderived from the monomers mentioned in JP 2010-204646 A. A structuralunit represented by any one of formula (a2-1-1) to formula (a2-1-6) ispreferable, a structural unit represented by any one of formula (a2-1-1)to formula (a2-1-4) is more preferable, and a structural unitrepresented by formula (a2-1-1) or formula (a2-1-3) is still morepreferable.

When the resin (A) includes the structural unit (a2-1), the content isusually 1 to 45 mol %, preferably 1 to 40 mol %, more preferably 1 to 35mol %, still more preferably 1 to 20 mol %, and yet more preferably 1 to10 mol %, based on all structural units of the resin (A).

<Structural Unit (a3)>

The lactone ring possessed by the structural unit (a3) may be amonocyclic ring such as a β-propiolactone ring, a γ-butyrolactone ringor a δ-valerolactone ring, or a condensed ring of a monocyclic lactonering and the other ring. Preferably, a γ-butyrolactone ring, anadamantanelactone ring or a bridged ring including a γ-butyrolactonering structure (e.g. a structural unit represented by the followingformula (a3-2)) is exemplified.

The structural unit (a3) is preferably a structural unit represented byformula (a3-1), formula (a3-2), formula (a3-3) or formula (a3-4). Thesestructural units may be included alone, or two or more structural unitsmay be included:

wherein, in formula (a3-1), formula (a3-2), formula (a3-3) and formula(a3-4),

L^(a4), Las and L^(a6) each independently represent —O— or a grouprepresented by *—O—(CH₂)_(k3)—CO—O— (k3 represents an integer of 1 to7),

L^(a7) represents —O—, *—O-L^(a8)-O—, *—O-L^(a8)-CO—O—,*—O-L^(a8)-CO—O-L^(a9)-CO—O— or *—O-L^(a8)-O—CO-L^(a9)-O—,

Las and L^(a9) each independently represent an alkanediyl group having 1to 6 carbon atoms,

* represents a bonding site to a carbonyl group,

R^(a18), R^(a19) and R^(a20) each independently represent a hydrogenatom or a methyl group,

R^(a24) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom,

X^(a3) represents —CH₂— or an oxygen atom,

R^(a21) represents an aliphatic hydrocarbon group having 1 to 4 carbonatoms,

R^(a22), R^(a23) and R^(a25) each independently represent a carboxygroup, a cyano group or an aliphatic hydrocarbon group having 1 to 4carbon atoms,

p1 represents an integer of 0 to 5,

q1 represents an integer of 0 to 3,

r1 represents an integer of 0 to 3,

w1 represents an integer of 0 to 8, and

when p1, q1, r1 and/or w1 is/are 2 or more, a plurality of R^(a21),R^(a22), R^(a23) and/or R^(a25) may be the same or different from eachother.

Examples of the aliphatic hydrocarbon group in R^(a21), R^(a22), R^(a23)and R^(a25) include alkyl groups such as a methyl group, an ethyl group,a propyl group, an isopropyl group, a butyl group, a sec-butyl group anda tert-butyl group.

Examples of the halogen atom in R^(a24) include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group in R^(a24) include a methyl group, an ethylgroup, a propyl group, an isopropyl group, a butyl group, a sec-butylgroup, a tert-butyl group, a pentyl group and a hexyl group, and thealkyl group is preferably an alkyl group having 1 to 4 carbon atoms, andmore preferably a methyl group or an ethyl group.

Examples of the alkyl group having a halogen atom in R^(a24) include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl group, atriiodomethyl group and the like.

Examples of the alkanediyl group in Las and L^(a9) include a methylenegroup, an ethylene group, a propane-1,3-diyl group, a propane-1,2-diylgroup, a butane-1,4-diyl group, a pentane-1,5-diyl group, ahexane-1,6-diyl group, a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group.

In formula (a3-1) to formula (a3-3), preferably, L^(a4) to L^(a6) areeach independently —O— or a group in which k3 is an integer of 1 to 4 in*—O—(CH₂)_(k3)—CO—O—, more preferably —O— and *—O—CH₂—CO—O—, and stillmore preferably an oxygen atom,

R^(a18) to R^(a21) are preferably a methyl group,

preferably, R^(a22) and R^(a23) are each independently a carboxy group,a cyano group or a methyl group, and

preferably, p1, q1 and r1 are each independently an integer of 0 to 2,and more preferably 0 or 1.

In formula (a3-4), R^(a24) is preferably a hydrogen atom or an alkylgroup having 1 to 4 carbon atoms, more preferably a hydrogen atom, amethyl group or an ethyl group, and still more preferably a hydrogenatom or a methyl group,

R^(a25) is preferably a carboxy group, a cyano group or a methyl group,

L^(a7) is preferably —O— or *—O-L^(a)s-CO—O—, and more preferably —O—,—O—CH₂—CO—O— or —O—C₂H₄—CO—O—, and

w1 is preferably an integer of 0 to 2, and more preferably 0 or 1.

Particularly, formula (a3-4) is preferably formula (a3-4)′:

wherein R^(a24) and L^(a7) are the same as defined above.

Examples of the structural unit (a3) include structural units derivedfrom the monomers mentioned in JP 2010-204646 A, the monomers mentionedin JP 2000-122294 A and the monomers mentioned in JP 2012-41274 A. Thestructural unit (a3) is preferably a structural unit represented by anyone of formula (a3-1-1), formula (a3-1-2), formula (a3-2-1), formula(a3-2-2), formula (a3-3-1), formula (a3-3-2) and formula (a3-4-1) toformula (a3-4-12), and structural units in which methyl groupscorresponding to R^(a18), R^(a19), R^(a20) and R^(a24) in formula (a3-1)to formula (a3-4) are substituted with hydrogen atoms in the abovestructural units.

When the resin (A) includes the structural unit (a3), the total contentis usually 5 to 70 mol %, preferably 10 to 65 mol %, and more preferably10 to 60 mol %, based on all structural units of the resin (A).

Each content of the structural unit (a3-1), the structural unit (a3-2),the structural unit (a3-3) or the structural unit (a3-4) is preferably 5to 60 mol %, more preferably 5 to 50 mol %, and still more preferably 10to 50 mol %, based on all structural units of the resin (A).

<Structural Unit (a4)>

Examples of the structural unit (a4) include the following structuralunit:

wherein, in formula (a4),

R⁴¹ represents a hydrogen atom or a methyl group, and

R⁴² represents a saturated hydrocarbon group having 1 to 24 carbon atomswhich has a halogen atom, and —CH₂— included in the saturatedhydrocarbon group may be replaced by —O— or —CO—.

Examples of the saturated hydrocarbon group represented by R⁴² include achain saturated hydrocarbon group and a monocyclic or polycyclicalicyclic saturated hydrocarbon group, and groups formed by combiningthese groups.

Examples of the chain saturated hydrocarbon group include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a decyl group, a dodecylgroup, a pentadecyl group, a hexadecyl group, a heptadecyl group and anoctadecyl group.

Examples of the monocyclic or polycyclic alicyclic saturated hydrocarbongroup include cycloalkyl groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic saturated hydrocarbon groups such as adecahydronaphthyl group, an adamantyl group, a norbornyl group and thefollowing groups (* represents a bonding site).

Examples of the group formed by combination include groups formed bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic saturated hydrocarbon groups, and include an-alkanediyl group-alicyclic saturated hydrocarbon group, an -alicyclicsaturated hydrocarbon group-alkyl group, an -alkanediyl group-alicyclicsaturated hydrocarbon group-alkyl group and the like.

Examples of the structural unit (a4) include a structural unitrepresented by formula (a4-0), a structural unit represented by formula(a4-1) and a structural unit represented by formula (a4-4):

wherein, in formula (a4-0),

R⁵⁴ represents a hydrogen atom or a methyl group,

L⁴a represents a single bond or an alkanediyl group having 1 to 4 carbonatoms,

L³a represents a perfluoroalkanediyl group having 1 to 8 carbon atoms ora perfluorocycloalkanediyl group having 3 to 12 carbon atoms, and

R⁶⁴ represents a hydrogen atom or a fluorine atom.

Examples of the alkanediyl group in L⁴a include linear alkanediyl groupssuch as a methylene group, an ethylene group, a propane-1,3-diyl groupand a butane-1,4-diyl group; and branched alkanediyl groups such as anethane-1,1-diyl group, a propane-1,2-diyl group, a butane-1,3-diylgroup, a 2-methylpropane-1,3-diyl group and a 2-methylpropane-1,2-diylgroup.

Examples of the perfluoroalkanediyl group in L³a include adifluoromethylene group, a perfluoroethylene group, aperfluoroethylfluoromethylene group, a perfluoropropane-1,3-diyl group,a perfluoropropane-1,2-diyl group, a perfluoropropane-2,2-diyl group, aperfluorobutane-1,4-diyl group, a perfluorobutane-2,2-diyl group, aperfluorobutane-1,2-diyl group, a perfluoropentane-1,5-diyl group, aperfluoropentane-2,2-diyl group, a perfluoropentane-3,3-diyl group, aperfluorohexane-1,6-diyl group, a perfluorohexane-2,2-diyl group, aperfluorohexane-3,3-diyl group, a perfluoroheptane-1,7-diyl group, aperfluoroheptane-2,2-diyl group, a perfluoroheptane-3,4-diyl group, aperfluoroheptane-4,4-diyl group, a perfluorooctane-1,8-diyl group, aperfluorooctane-2,2-diyl group, a perfluorooctane-3,3-diyl group, aperfluorooctane-4,4-diyl group and the like.

Examples of the perfluorocycloalkanediyl group in L³a include aperfluorocyclohexanediyl group, a perfluorocyclopentanediyl group, aperfluorocycloheptanediyl group, a perfluoroadamantanediyl group and thelike.

L⁴a is preferably a single bond, a methylene group or an ethylene group,and more preferably a single bond or a methylene group.

L³a is preferably a perfluoroalkanediyl group having 1 to 6 carbonatoms, and more preferably a perfluoroalkanediyl group having 1 to 3carbon atoms.

Examples of the structural unit (a4-0) include the following structuralunits, and structural units in which a methyl group corresponding to R⁵⁴in the structural unit (a4-0) in the following structural units issubstituted with a hydrogen atom:

wherein, in formula (a4-1),

R^(a41) represents a hydrogen atom or a methyl group,

R^(a42) represents a saturated hydrocarbon group having 1 to 20 carbonatoms which may have a substituent, and —CH₂— included in the saturatedhydrocarbon group may be replaced by —O— or —CO—,

A^(a41) represents an alkanediyl group having 1 to 6 carbon atoms whichmay have a substituent or a group represented by formula (a-g1), inwhich at least one of A^(a41) and R^(a42) has, as a substituent, ahalogen atom (preferably a fluorine atom):

[in which, in formula (a-g1),

s represents 0 or 1,

A^(a42) and A^(a44) each independently represent a divalent saturatedhydrocarbon group having 1 to 5 carbon atoms which may have asubstituent,

A^(a43) represents a single bond or a divalent saturated hydrocarbongroup having 1 to 5 carbon atoms which may have a substituent,

X^(a41) and X^(a42) each independently represent —O—, —CO—, —CO—O— or—O—CO—, in which the total number of carbon atoms of A^(a42), A^(a43),A^(a44), X^(a41) and X^(a42) is 7 or less], and

* represents a bonding site and * at the right side represents a bondingsite to —O—CO—R^(a42),

Examples of the saturated hydrocarbon group in R^(a42) include a chainsaturated hydrocarbon group and a monocyclic or polycyclic alicyclicsaturated hydrocarbon group, and groups formed by combining thesegroups.

Examples of the chain saturated hydrocarbon group include a methylgroup, an ethyl group, a propyl group, a butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a decyl group, a dodecylgroup, a pentadecyl group, a hexadecyl group, a heptadecyl group and anoctadecyl group.

Examples of the monocyclic or polycyclic alicyclic saturated hydrocarbongroup include cycloalkyl groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic saturated hydrocarbon groups such as adecahydronaphthyl group, an adamantyl group, a norbornyl group and thefollowing groups (* represents a bonding site).

Examples of the group formed by combination include groups formed bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic saturated hydrocarbon groups, and include an-alkanediyl group-alicyclic saturated hydrocarbon group, an -alicyclicsaturated hydrocarbon group-alkyl group, an -alkanediyl group-alicyclicsaturated hydrocarbon group-alkyl group and the like.

Examples of the substituent which is possessed by R^(a42) include atleast one selected from the group consisting of a halogen atom and agroup represented by formula (a-g3). Examples of the halogen atominclude a fluorine atom, a chlorine atom, a bromine atom and an iodineatom, and a

fluorine atom is preferable:

*—X^(a43)-A^(a45)  (a-g3)

wherein, in formula (a-g3),

X^(a43) represents an oxygen atom, a carbonyl group, *—O—CO— or *—CO—O—,

A^(a45) represents a saturated hydrocarbon group having 1 to 17 carbonatoms which may have a halogen atom, and

* represents a bonding site to R^(a42).

In R^(a42)—X^(a4)3-A^(a43), when R^(a42) has no halogen atom, A^(a45)represents a saturated hydrocarbon group having 1 to 17 carbon atomshaving at least one halogen atom.

Examples of the saturated hydrocarbon group in A^(a45) include alkylgroups such as a methyl group, an ethyl group, a propyl group, a butylgroup, a pentyl group, a hexyl group, a heptyl group, an octyl group, adecyl group, a dodecyl group, a pentadecyl group, a hexadecyl group, aheptadecyl group and an octadecyl group;

monocyclic alicyclic hydrocarbon groups such as a cyclopentyl group, acyclohexyl group, a cycloheptyl group and a cyclooctyl group; andpolycyclic alicyclic hydrocarbon groups such as a decahydronaphthylgroup, an adamantyl group, a norbornyl group and the following groups (*represents a bonding site).

Examples of the group formed by combination include a group obtained bycombining one or more alkyl groups or one or more alkanediyl groups withone or more alicyclic hydrocarbon groups, and include an -alkanediylgroup-alicyclic hydrocarbon group, an -alicyclic hydrocarbon group-alkylgroup, an -alkanediyl group-alicyclic hydrocarbon group-alkyl group andthe like.

R^(a42) is preferably a saturated hydrocarbon group which may have ahalogen atom, and more preferably an alkyl group having a halogen atomand/or a saturated hydrocarbon group having a group represented byformula (a-g3).

When R^(a42) is a saturated hydrocarbon group having a halogen atom, asaturated hydrocarbon group having a fluorine atom is preferable, aperfluoroalkyl group or a perfluorocycloalkyl group is more preferable,a perfluoroalkyl group having 1 to 6 carbon atoms is still morepreferable, and a perfluoroalkyl group having 1 to 3 carbon atoms isparticularly preferable. Examples of the perfluoroalkyl group include aperfluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluorobutyl group, a perfluoropentyl group, a perfluorohexyl group,a perfluoroheptyl group and a perfluorooctyl group. Examples of theperfluorocycloalkyl group include a perfluorocyclohexyl group and thelike.

When R^(a42) is a saturated hydrocarbon group having a group representedby formula (a-g3), the total number of carbon atoms of R^(a42) ispreferably 15 or less, and more preferably 12 or less, including thenumber of carbon atoms included in the group represented by formula(a-g3). When having the group represented by formula (a-g3) as thesubstituent, the number thereof is preferably 1.

When R^(a42) is a saturated hydrocarbon group having the grouprepresented by formula (a-g3), R^(a42) is still more preferably a grouprepresented by formula (a-g2):

*-A^(a46)-X^(a44)-A^(a47)  (a-g2)

wherein, in formula (a-g2),

A^(a46) represents a divalent saturated hydrocarbon group having 1 to 17carbon atoms which may have a halogen atom,

X^(a44) represents **—O—CO— or **—CO—O— (** represents a bonding site toA^(a46)),

A^(a47) represents a saturated hydrocarbon group having 1 to 17 carbonatoms which may have a halogen atom,

the total number of carbon atoms of A^(a46), A^(a47) and X^(a44) is 18or less, and at least one of A^(a46) and A^(a47) has at least onehalogen atom, and

* represents a bonding site to a carbonyl group.

The number of carbon atoms of the saturated hydrocarbon group as forA^(a46) is preferably 1 to 6, and more preferably 1 to 3.

The number of carbon atoms of the saturated hydrocarbon group as forA^(a47) is preferably 4 to 15, and more preferably 5 to 12, and A^(a47)is still more preferably a cyclohexyl group or an adamantyl group.

Preferred structures of the group represented by formula (a-g2) are thefollowing structures (* represents a bonding site to a carbonyl group).

Examples of the alkanediyl group in A^(a41) include linear alkanediylgroups such as a methylene group, an ethylene group, a propane-1,3-diylgroup, a butane-1,4-diyl group, a pentane-1,5-diyl group and ahexane-1,6-diyl group; and branched alkanediyl groups such as apropane-1,2-diyl group, a butane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a 1-methylbutane-1,4-diyl group and a2-methylbutane-1,4-diyl group.

Examples of the substituent in the alkanediyl group represented byA^(a41) include a hydroxy group and an alkoxy group having 1 to 6 carbonatoms.

A^(a41) is preferably an alkanediyl group having 1 to 4 carbon atoms,more preferably an alkanediyl group having 2 to 4 carbon atoms, andstill more preferably an ethylene group.

Examples of the divalent saturated hydrocarbon group represented byA^(a42), A^(a43) and A^(a44) in the group represented by formula (a-g1)include a linear or branched alkanediyl group and a monocyclic divalentalicyclic saturated hydrocarbon group, and a divalent saturatedhydrocarbon group formed by combining an alkanediyl group and a divalentalicyclic saturated hydrocarbon group. Specific examples thereof includea methylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a1-methylpropane-1,3-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group and the like.

Examples of the substituent of the divalent saturated hydrocarbon grouprepresented by A^(a42), A^(a43) and A^(a44) include a hydroxy group andan alkoxy group having 1 to 6 carbon atoms.

s is preferably 0.

In the group represented by formula (a-g1), examples of the group inwhich X^(a42) is —O—, —CO—, —CO—O— or —O—CO-include the followinggroups. In the following exemplification, * and ** each represent abonding site, and ** represents a bonding site to —O—CO—R^(a42)

Examples of the structural unit represented by formula (a4-1) includethe following structural units, and structural units in which a methylgroup corresponding to R^(a41) in the structural unit represented byformula (a4-1) in the following structural units is substituted with ahydrogen atom.

Examples of the structural unit represented by formula (a4-1) include astructural unit represented by formula (a4-2) and a structural unitrepresented by formula (a4-3):

wherein, in formula (a4-2),

R^(f3) represents a hydrogen atom or a methyl group,

L⁴⁴ represents an alkanediyl group having 1 to 6 carbon atoms, and —CH₂—included in the alkanediyl group may be replaced by —O— or —CO—,

R^(f6) represents a saturated hydrocarbon group having 1 to 20 carbonatoms having a fluorine atom, and

the upper limit of the total number of carbon atoms of L⁴⁴ and R^(f6) is21.

Examples of the alkanediyl group having 1 to 6 carbon atoms of L⁴⁴include those which are the same as mentioned as for A^(a41)

Examples of the saturated hydrocarbon group of R^(f6) include the samegroups as mentioned for R⁴².

The alkanediyl group in L⁴⁴ is preferably an alkanediyl group having 2to 4 carbon atoms, and more preferably an ethylene group.

The structural unit represented by formula (a4-2) includes, for example,structural units represented by formula (a4-1-1) to formula (a4-1-11). Astructural unit in which a methyl group corresponding to R^(f5) in thestructural unit (a4-2) is substituted with a hydrogen atom is alsoexemplified as the structural unit represented by formula (a4-2):

wherein, in formula (a4-3),

R^(f7) represents a hydrogen atom or a methyl group,

L³ represents an alkanediyl group having 1 to 6 carbon atoms,

A^(f13) represents a divalent saturated hydrocarbon group having 1 to 18carbon atoms which may have a fluorine atom,

X^(f)1² represents *—O—CO— or *—CO—O— (* represents a bonding site toA^(f13)),

A^(f14) represents a saturated hydrocarbon group having 1 to 17 carbonatoms which may have a fluorine atom, and

at least one of A^(f13) and A^(f14) has a fluorine atom, and the upperlimit of the total number of carbon atoms of L⁵, A^(f13) and A^(f14) is20.

Examples of the alkanediyl group in L³ include those which are the sameas mentioned in the alkanediyl group as for A^(a41).

The divalent saturated hydrocarbon group which may have a fluorine atomin A^(f13) is preferably a divalent chain saturated hydrocarbon groupwhich may have a fluorine atom and a divalent alicyclic saturatedhydrocarbon group which may have a fluorine atom, and more preferably aperfluoroalkanediyl group.

Examples of the divalent chain saturated hydrocarbon group which mayhave a fluorine atom include alkanediyl groups such as a methylenegroup, an ethylene group, a propanediyl group, a butanediyl group and apentanediyl group; and perfluoroalkanediyl groups such as adifluoromethylene group, a perfluoroethylene group, aperfluoropropanediyl group, a perfluorobutanediyl group and aperfluoropentanediyl group.

The divalent alicyclic saturated hydrocarbon group which may have afluorine atom may be either monocyclic or polycyclic. Examples of themonocyclic group include a cyclohexanediyl group and aperfluorocyclohexanediyl group. Examples of the polycyclic group includean adamantanediyl group, a norbornanediyl group, aperfluoroadamantanediyl group and the like.

Examples of the saturated hydrocarbon group and the saturatedhydrocarbon group which may have a fluorine atom for A^(f14) include thesame groups as mentioned for R^(a42). Of these groups, preferable arefluorinated alkyl groups such as a trifluoromethyl group, adifluoromethyl group, a methyl group, a perfluoroethyl group, a2,2,2-trifluoroethyl group, a 1,1,2,2-tetrafluoroethyl group, an ethylgroup, a perfluoropropyl group, a 2,2,3,3,3-pentafluoropropyl group, apropyl group, a perfluorobutyl group, a 1,1,2,2,3,3,4,4-octafluorobutylgroup, a butyl group, a perfluoropentyl group, a2,2,3,3,4,4,5,5,5-nonafluoropentyl group, a pentyl group, a hexyl group,a perfluorohexyl group, a heptyl group, a perfluoroheptyl group, anoctyl group and a perfluorooctyl group; a cyclopropylmethyl group, acyclopropyl group, a cyclobutylmethyl group, a cyclopentyl group, acyclohexyl group, a perfluorocyclohexyl group, an adamantyl group, anadamantylmethyl group, an adamantyldimethyl group, a norbornyl group, anorbornylmethyl group, a perfluoroadamantyl group, aperfluoroadamantylmethyl group and the like.

In formula (a4-3), L³ is preferably an ethylene group.

The divalent saturated hydrocarbon group of A^(f13) is preferably agroup including a divalent chain saturated hydrocarbon group having 1 to6 carbon atoms and a divalent alicyclic saturated hydrocarbon grouphaving 3 to 12 carbon atoms, and more preferably a divalent chainsaturated hydrocarbon group having 2 to 3 carbon atoms.

The saturated hydrocarbon group of A^(f14) is preferably a groupincluding a chain saturated hydrocarbon group having 3 to 12 carbonatoms and an alicyclic saturated hydrocarbon group having 3 to 12 carbonatoms, and more preferably a group including a chain saturatedhydrocarbon group having 3 to 10 carbon atoms and an alicyclic saturatedhydrocarbon group having 3 to 10 carbon atoms. Of these groups, A^(f14)is preferably a group including an alicyclic saturated hydrocarbon grouphaving 3 to 12 carbon atoms, and more preferably a cyclopropylmethylgroup, a cyclopentyl group, a cyclohexyl group, a norbornyl group and anadamantyl group.

The structural unit represented by formula (a4-3) includes, for example,structural units represented by formula (a4-1′-1) to formula (a4-1′-11).A structural unit in which a methyl group corresponding to R^(f7) in thestructural unit (a4-3) is substituted with a hydrogen atom is alsoexemplified as the structural unit represented by formula (a4-3).

It is also possible to exemplify, as the structural unit (a4), astructural unit represented by formula (a4-4):

wherein, in formula (a4-4),

R^(f21) represents a hydrogen atom or a methyl group,

A^(f21) represents —(CH₂)_(j1)—, —(CH₂)_(j2)—O—(CH₂)_(j3)— or—(CH₂)_(j4)—CO—O— (CH₂)_(j5)-j1 to j5 each independently represent aninteger of 1 to 6, and

R^(f22) represents a saturated hydrocarbon group having 1 to 10 carbonatoms having a fluorine atom.

Examples of the saturated hydrocarbon group of R^(f22) include thosewhich are the same as the saturated hydrocarbon group represented byR^(a42). R^(f22) is preferably an alkyl group having 1 to 10 carbonatoms which has a fluorine atom or an alicyclic saturated hydrocarbongroup having 1 to 10 carbon atoms which has a fluorine atom, morepreferably an alkyl group having 1 to 10 carbon atoms which has afluorine atom, and still more preferably an alkyl group having 1 to 6carbon atoms which has a fluorine atom.

In formula (a4-4), A^(f21) is preferably —(CH₂)_(j1)—, more preferablyan ethylene group or a methylene group, and still more preferably amethylene group.

The structural unit represented by formula (a4-4) includes, for example,the following structural units and structural units in which a methylgroup corresponding to R^(f21) in the structural unit (a4-4) issubstituted with a hydrogen atom in structural units represented by thefollowing formulas.

When the resin (A) includes the structural unit (a4), the content ispreferably 1 to 20 mol %, more preferably 2 to 15 mol %, and still morepreferably 3 to 10 mol %, based on all structural units of the resin(A).

<Structural Unit (a5)>

Examples of a non-leaving hydrocarbon group possessed by the structuralunit (a5) include groups having a linear, branched or cyclic hydrocarbongroup. Of these, the structural unit (a5) is preferably a group havingan alicyclic hydrocarbon group.

The structural unit (a5) includes, for example, a structural unitrepresented by formula (a5-1):

wherein, in formula (a5-1),

R⁵¹ represents a hydrogen atom or a methyl group,

R⁵² represents an alicyclic hydrocarbon group having 3 to 18 carbonatoms, and a hydrogen atom included in the alicyclic hydrocarbon groupmay be substituted with an aliphatic hydrocarbon group having 1 to 8carbon atoms, and

L⁵³ represents a single bond or a divalent saturated hydrocarbon grouphaving 1 to 18 carbon atoms, and —CH₂— included in the saturatedhydrocarbon group may be replaced by —O— or —CO—.

The alicyclic hydrocarbon group in R⁵² may be either monocyclic orpolycyclic. The monocyclic alicyclic hydrocarbon group includes, forexample, a cyclopropyl group, a cyclobutyl group, a cyclopentyl groupand a cyclohexyl group. The polycyclic alicyclic hydrocarbon groupincludes, for example, an adamantyl group and a norbornyl group.

The aliphatic hydrocarbon group having 1 to 8 carbon atoms includes, forexample, alkyl groups such as a methyl group, an ethyl group, a propylgroup, an isopropyl group, a butyl group, a sec-butyl group, atert-butyl group, a pentyl group, a hexyl group, an octyl group and a2-ethylhexyl group.

Examples of the alicyclic hydrocarbon group having a substituentincludes a 3-methyladamantyl group and the like.

R⁵² is preferably an unsubstituted alicyclic hydrocarbon group having 3to 18 carbon atoms, and more preferably an adamantyl group, a norbornylgroup or a cyclohexyl group.

Examples of the divalent saturated hydrocarbon group in L⁵⁵ include adivalent chain saturated hydrocarbon group and a divalent alicyclicsaturated hydrocarbon group, and a divalent chain saturated hydrocarbongroup is preferable.

The divalent chain saturated hydrocarbon group includes, for example,alkanediyl groups such as a methylene group, an ethylene group, apropanediyl group, a butanediyl group and a pentanediyl group.

The divalent alicyclic saturated hydrocarbon group may be eithermonocyclic or polycyclic. Examples of the monocyclic alicyclic saturatedhydrocarbon group include cycloalkanediyl groups such as acyclopentanediyl group and a cyclohexanediyl group. Examples of thepolycyclic divalent alicyclic saturated hydrocarbon group include anadamantanediyl group and a norbornanediyl group.

The group in which —CH₂— included in the divalent saturated hydrocarbongroup represented by L⁵³ is replaced by —O— or —CO— includes, forexample, groups represented by formula (L1-1) to formula (L1-4). In thefollowing formulas, * and ** each represent a bonding site, and *represents a bonding site to an oxygen atom.

In formula (L1-1),

X^(x1) represents *—O—CO— or *—CO—O— (* represents a bonding site toL^(x1)),

L^(x1) represents a divalent aliphatic saturated hydrocarbon grouphaving 1 to 16 carbon atoms,

L^(x2) represents a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 15 carbon atoms, and

the total number of carbon atoms of L^(x1) and L^(x2) is 16 or less.

In formula (L1-2),

L^(x3) represents a divalent aliphatic saturated hydrocarbon grouphaving 1 to 17 carbon atoms,

L^(x4) represents a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 16 carbon atoms, and

the total number of carbon atoms of L^(x3) and L^(x4) is 17 or less.

In formula (L1-3),

L^(x5) represents a divalent aliphatic saturated hydrocarbon grouphaving 1 to 15 carbon atoms,

L^(x6) and L^(x7) each independently represent a single bond or adivalent aliphatic saturated hydrocarbon group having 1 to 14 carbonatoms, and

the total number of carbon atoms of L^(x5), L^(x6) and L^(x7) is 15 orless.

In formula (L1-4),

L^(x8) and L^(x9) represent a single bond or a divalent aliphaticsaturated hydrocarbon group having 1 to 12 carbon atoms,

W^(x1) represents a divalent alicyclic saturated hydrocarbon grouphaving 3 to 15 carbon atoms, and

the total number of carbon atoms of L^(x8), L^(x9) and W^(x1) is 15 orless.

L^(x1) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms, and more preferably a methylene group or anethylene group.

L^(x2) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond.

L^(x3) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms.

L^(x4) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms.

L^(x5) is preferably a divalent aliphatic saturated hydrocarbon grouphaving 1 to 8 carbon atoms, and more preferably a methylene group or anethylene group.

L^(x6) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably amethylene group or an ethylene group.

L^(x7) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms.

L^(x8) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond or a methylene group.

L^(x9) is preferably a single bond or a divalent aliphatic saturatedhydrocarbon group having 1 to 8 carbon atoms, and more preferably asingle bond or a methylene group.

W^(x1) is preferably a divalent alicyclic saturated hydrocarbon grouphaving 3 to 10 carbon atoms, and more preferably a cyclohexanediyl groupor an adamantanediyl group.

The group represented by formula (L1-1) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-2) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-3) includes, for example, thefollowing divalent groups.

The group represented by formula (L1-4) includes, for example, thefollowing divalent groups.

L⁵³ is preferably a single bond or a group represented by formula(L1-1).

Examples of the structural unit (a5-1) include the following structuralunits and structural units in which a methyl group corresponding to R⁵¹in the structural unit (a5-1) in the following structural units issubstituted with a hydrogen atom.

When the resin (A) includes the structural unit (a5), the content ispreferably 1 to 30 mol %, more preferably 2 to 20 mol %, and still morepreferably 3 to 15 mol %, based on all structural units of the resin(A).

<Structural Unit (a6)>

The structural unit (a6) is a structural unit having an —SO₂— group, andit is preferable to have an —SO₂— group in a side chain.

The structural unit having an —SO₂— group may have a linear structurehaving an —SO₂— group, a branched structure having an —SO₂— group, or acyclic structure (monocyclic and polycyclic structure) having an —SO₂—group. The structural unit is preferably a structural unit which has acyclic structure having an —SO₂— group, and more preferably a structuralunit which has a cyclic structure (sultone ring) having —SO₂—O—.

Examples of the sultone ring include rings represented by the followingformula (T1-1), formula (T1-2), formula (T1-3) and formula (T1-4). Thebonding site can be any position. The sultone ring may be monocyclic,and is preferably polycyclic. The polycyclic sultone ring means abridged ring which has —SO₂—O— as an atomic group constituting the ring,and examples thereof include rings represented by formula (T1-1) andformula (T1-2). The sultone ring may have, as the atomic groupconstituting the ring, a heteroatom, in addition to —SO₂—O—, like thering represented by formula (T1-2). Examples of the heteroatom includean oxygen atom, a sulfur atom or a nitrogen atom, and an oxygen atom ispreferable.

The sultone ring may have a substituent, and examples of the substituentinclude an alkyl group having 1 to 12 carbon atoms which may have ahalogen atom or a hydroxy group, a halogen atom, a hydroxy group, acyano group, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbonatoms, a glycidyloxy group, an alkoxycarbonyl group having 2 to 12carbon atoms and an alkylcarbonyl group having 2 to 4 carbon atoms.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and an iodine atom.

Examples of the alkyl group include a methyl group, an ethyl group, apropyl group, a butyl group, a pentyl group, a hexyl group, an octylgroup and a decyl group, and the alkyl group is preferably an alkylgroup having 1 to 6 carbon atoms, and more preferably a methyl group.

Examples of the alkyl group having a halogen atom include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl groupand a triiodomethyl group, and a trifluoromethyl group is preferable.

Examples of the alkyl group having a hydroxy group include hydroxyalkylgroups such as a hydroxymethyl group and a 2-hydroxyethyl group.

Examples of the alkoxy group include a methoxy group, an ethoxy group, apropoxy group, a butoxy group, a pentyloxy group, a hexyloxy group, aheptyloxy group, an octyloxy group, a decyloxy group and a dodecyloxygroup.

Examples of the aryl group include a phenyl group, a naphthyl group, ananthryl group, a p-methylphenyl group, a p-tert-butylphenyl group, ap-adamantylphenyl group, a tolyl group, a xylyl group, a cumyl group, amesityl group, a biphenyl group, a phenanthryl group, a2,6-diethylphenyl group and a 2-methyl-6-ethylphenyl group.

Examples of the aralkyl group include a benzyl group, a phenethyl group,a phenylpropyl group, a naphthylmethyl group and a naphthylethyl group.

Examples of the alkoxycarbonyl group include groups in which an alkoxygroup is bonded with a carbonyl group, such as a methoxycarbonyl groupor an ethoxycarbonyl group, and preferably include an alkoxycarbonylgroup having 6 or less carbon atoms and more preferably include amethoxycarbonyl group.

Examples of the alkylcarbonyl group include an acetyl group, a propionylgroup and a butyryl group.

From the viewpoint that it is easy to produce a monomer from which thestructural unit (a6) is derived, a sultone ring having no substituent ispreferable.

The sultone ring is preferably a ring represented by the followingformula (T1′):

wherein, in formula (T1′),

X¹¹ represents an oxygen atom, a sulfur atom or a methylene group,

R⁴¹ represents an alkyl group having 1 to 12 carbon atoms which may havea halogen atom or a hydroxy group, a halogen atom, a hydroxy group, acyano group, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbonatoms, a glycidyloxy group, an alkoxycarbonyl group having 2 to 12carbon atoms, or an alkylcarbonyl group having 2 to 4 carbon atoms,

ma represents an integer of 0 to 9, and when ma is 2 or more, aplurality of R⁴¹ may be the same or different, and

the bonding site may be at any position.

X¹¹ is preferably an oxygen atom or a methylene group, and morepreferably a methylene group.

Examples of R⁴¹ include those which are the same as the substituent ofthe sultone ring, and an alkyl group having 1 to 12 carbon atoms whichmay have a halogen atom or a hydroxy group is preferable.

The sultone ring is more preferably a ring represented by formula (T1):

wherein, in formula (T1),

R⁸ represents an alkyl group having 1 to 12 carbon atoms which may havea halogen atom or a hydroxy group, a halogen atom, a hydroxy group, acyano group, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbonatoms, a glycidyloxy group, an alkoxycarbonyl group having 2 to 12carbon atoms, or an alkylcarbonyl group having 2 to 4 carbon atoms,

m represents an integer of 0 to 9, and when m is 2 or more, a pluralityof R⁸ may be the same or different, and

the bonding site may be at any position.

Examples of R⁸ include those which are the same as for R⁴1.

ma in formula (T1′) and m in formula (T1) are preferably 0 or 1, andmore preferably 0.

Examples of the ring represented by formula (T1′) and the ringrepresented by formula (T1) include the following rings. The bondingsite may be at any position.

It is preferable that the structural unit having a sultone ring has thefollowing groups. * in the following groups represents a bonding site.

It is preferable that the structural unit having an —SO₂— group furtherhas a group derived from a polymerizable group. Examples of thepolymerizable group include a vinyl group, an acryloyl group, amethacryloyl group, an acryloyloxy group, a methacryloyloxy group, anacryloylamino group, a methacryloylamino group, an acryloylthio group, amethacryloylthio group and the like.

Particularly, the monomer from which the structural unit (a6) is derivedis preferably a monomer having an ethylenically unsaturated bond, andmore preferably a (meth) acrylic monomer.

The structural unit (a6) is preferably a structural unit represented byformula (Ix):

wherein, in formula (Ix), R^(x) represents an alkyl group having 1 to 6carbon atoms which may have a halogen atom, a hydrogen atom or a halogenatom,

A^(xx) represents an oxygen atom, —N(R^(c))— or a sulfur atom,

A^(x) represents a divalent saturated hydrocarbon group having 1 to 18carbon atoms, and —CH₂— included in the saturated hydrocarbon group maybe replaced by —O—, —CO— or —N(R^(d))—,

X¹¹ represents an oxygen atom, a sulfur atom or a methylene group,

R⁴¹ represents an alkyl group having 1 to 12 carbon atoms which may havea halogen atom or a hydroxy group, a halogen atom, a hydroxy group, acyano group, an alkoxy group having 1 to 12 carbon atoms, an aryl grouphaving 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbonatoms, a glycidyloxy group, an alkoxycarbonyl group having 2 to 12carbon atoms, or an alkylcarbonyl group having 2 to 4 carbon atoms,

ma represents an integer of 0 to 9, and when ma is 2 or more, aplurality of R⁴¹ may be the same or different, and

R^(c) and R^(d) each independently represent a hydrogen atom or an alkylgroup having 1 to 6 carbon atoms.

Examples of the halogen atom as for R^(x) include a fluorine atom, achlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group as for R^(x) include a methyl group, anethyl group, an n-propyl group, an isopropyl group, an n-butyl group, asec-butyl group, a tert-butyl group, an n-pentyl group and an n-hexylgroup, and an alkyl group having 1 to 4 carbon atoms is preferable, anda methyl group or an ethyl group is more preferable.

Examples of the alkyl group having a halogen atom as for R^(x) include atrifluoromethyl group, a perfluoroethyl group, a perfluoropropyl group,a perfluoroisopropyl group, a perfluorobutyl group, a perfluorosec-butylgroup, a perfluorotert-butyl group, a perfluoropentyl group, aperfluorohexyl group, a trichloromethyl group, a tribromomethyl groupand a triiodomethyl group.

R^(x) is preferably a hydrogen atom or an alkyl group having 1 to 4carbon atoms, more preferably a hydrogen atom, a methyl group or anethyl group, and still more preferably a hydrogen atom or a methylgroup.

Examples of the divalent saturated hydrocarbon group as for A^(x)include a linear alkanediyl group, a branched alkanediyl group and amonocyclic or polycyclic divalent alicyclic saturated hydrocarbon group,and the divalent saturated hydrocarbon group may be those obtained bycombining two or more of these groups.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, an undecane-1,11-diyl group, a dodecane-1,12-diyl group, atridecane-1,13-diyl group, a tetradecane-1,14-diyl group, apentadecane-1,15-diyl group, a hexadecane-1,16-diyl group, aheptadecane-1,17-diyl group, an ethane-1,1-diyl group, apropane-1,1-diyl group and a propane-2,2-diyl group;

branched alkanediyl groups such as a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group;

monocyclic divalent alicyclic saturated hydrocarbon groups which arecycloalkanediyl groups such as a cyclobutane-1,3-diyl group, acyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group and acyclooctane-1,5-diyl group; and

polycyclic divalent alicyclic saturated hydrocarbon groups such as anorbornane-1,4-diyl group, a norbornane-2,5-diyl group, anadamantane-1,5-diyl group and an adamantane-2,6-diyl group.

Examples of R⁴¹, X¹¹ and ma include those which are the same as informula (T1′).

Examples of the sultone ring include those mentioned above, and ofthese, preferred are the above-mentioned rings in which the bonding siteis specified.

Examples of the structural unit (a6) include the following structuralunits.

Of these, structural units represented by formula (a6-1), formula(a6-2), formula (a6-6), formula (a6-7), formula (a6-8) and formula(a6-12) are preferable, and structural units represented by formula(a6-1), formula (a6-2), formula (a6-7) and (a6-8) are more preferable.

When the resin (A) includes the structural unit (a6), the content ispreferably 1 to 50 mol %, more preferably 2 to 40 mol %, and still morepreferably 3 to 30 mol %, based on all structural units of the resin(A).

<Structural Unit (II)>

The resin (A) may further include a structural unit which is decomposedupon exposure to radiation to generate an acid (hereinafter sometimesreferred to as “structural unit (II)”). Specific examples of thestructural unit (II) include the structural units mentioned in JP2016-79235 A, and a structural unit having a sulfonate group or acarboxylate group and an organic cation in a side chain or a structuralunit having a sulfonio group and an organic anion in a side chain arepreferable.

The structural unit having a sulfonate group or a carboxylate group andan organic cation in a side chain is preferably a structural unitrepresented by formula (II-2-A′):

wherein, in formula (II-2-A′),

X^(III3) represents a divalent saturated hydrocarbon group having 1 to18 carbon atoms, —CH₂— included in the saturated hydrocarbon group maybe replaced by —O—, —S— or —CO—, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a halogen atom, analkyl group having 1 to 6 carbon atoms which may have a halogen atom, ora hydroxy group,

A^(x1) represents an alkanediyl group having 1 to 8 carbon atoms, and ahydrogen atom included in the alkanediyl group may be substituted with afluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms,

RA⁻ represents a sulfonate group or a carboxylate group,

R^(III3) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom, and

ZA⁺ represents an organic cation.

Examples of the halogen atom represented by R^(III3) include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom represented by R^(III3) include those which are the same asthe alkyl group having 1 to 6 carbon atoms which may have a halogen atomrepresented by Rae,

Examples of the alkanediyl group having 1 to 8 carbon atoms representedby A^(x1) include a methylene group, an ethylene group, apropane-1,3-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, an ethane-1,1-diyl group, apropane-1,1-diyl group, a propane-1,2-diyl group, a propane-2,2-diylgroup, a pentane-2,4-diyl group, a 2-methylpropane-1,3-diyl group, a2-methylpropane-1,2-diyl group, a pentane-1,4-diyl group, a2-methylbutane-1,4-diyl group and the like.

Examples of the perfluoroalkyl group having 1 to 6 carbon atoms whichmay be substituted in A^(x1) include a trifluoromethyl group, aperfluoroethyl group, a perfluoropropyl group, a perfluoroisopropylgroup, a perfluorobutyl group, a perfluorosec-butyl group, aperfluorotert-butyl group, a perfluoropentyl group, a perfluorohexylgroup and the like.

Examples of the divalent saturated hydrocarbon group having 1 to 18carbon atoms represented by X^(III3) include a linear or branchedalkanediyl group, a monocyclic or polycyclic divalent alicyclicsaturated hydrocarbon group, or a combination thereof.

Specific examples thereof include linear alkanediyl groups such as amethylene group, an ethylene group, a propane-1,3-diyl group, apropane-1,2-diyl group, a butane-1,4-diyl group, a pentane-1,5-diylgroup, a hexane-1,6-diyl group, a heptane-1,7-diyl group, anoctane-1,8-diyl group, a nonane-1,9-diyl group, a decane-1,10-diylgroup, an undecane-1,11-diyl group and a dodecane-1,12-diyl group;branched alkanediyl groups such as a butane-1,3-diyl group, a2-methylpropane-1,3-diyl group, a 2-methylpropane-1,2-diyl group, apentane-1,4-diyl group and a 2-methylbutane-1,4-diyl group; divalentmonocyclic alicyclic saturated hydrocarbon groups, for example,cycloalkanediyl groups such as a cyclobutane-1,3-diyl group, acyclopentane-1,3-diyl group, a cyclohexane-1,4-diyl group and acyclooctane-1,5-diyl group; and divalent polycyclic alicyclic saturatedhydrocarbon groups such as a norbornane-1,4-diyl group, anorbornane-2,5-diyl group, an adamantane-1,5-diyl group and anadamantane-2,6-diyl group.

Those in which —CH₂— included in the saturated hydrocarbon group arereplaced by —O—, —S— or —CO— include, for example, divalent groupsrepresented by formula (X1) to formula (X53). Before replacing —CH₂—included in the saturated hydrocarbon group by —O—, —S— or —CO—, thenumber of carbon atoms is 17 or less. In the following formulas, * and** represent a bonding site, and * represents a bonding site to A^(x) 1.

X³ represents a divalent saturated hydrocarbon group having 1 to 16carbon atoms.

X⁴ represents a divalent saturated hydrocarbon group having 1 to 15carbon atoms.

X⁵ represents a divalent saturated hydrocarbon group having 1 to 13carbon atoms.

X⁶ represents a divalent saturated hydrocarbon group having 1 to 14carbon atoms.

X⁷ represents a trivalent saturated hydrocarbon group having 1 to 14carbon atoms.

X⁸ represents a divalent saturated hydrocarbon group having 1 to 13carbon atoms.

Examples of the organic cation represented by ZA⁺ include an organiconium cation, an organic sulfonium cation, an organic iodonium cation,an organic ammonium cation, a benzothiazolium cation and an organicphosphonium cation. Of these, an organic sulfonium cation and an organiciodonium cation are preferable, and an aryl sulfonium cation is morepreferable. Specific examples thereof include a cation represented byany one of the above-mentioned formula (b2-1) to formula (b2-4)(hereinafter sometimes referred to as “cation (b2-1)” according to thenumber of formula).

The structural unit represented by formula (II-2-A′) is preferably astructural unit represented by formula (II-2-A):

wherein, in formula (II-2-A),

R^(III3), X^(III3) and ZA⁺ are the same as defined above,

z represents an integer of 0 to 6,

R^(III2) and R^(III4) each independently represent a hydrogen atom, afluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms, andwhen z is 2 or more, a plurality of R^(III2) and R^(III4) may be thesame or different form each other, and

Q^(a) and Q^(b) each independently represent a fluorine atom or aperfluoroalkyl group having 1 to 6 carbon atoms.

Examples of the perfluoroalkyl group having 1 to 6 carbon atomsrepresented by R^(III2), R^(III4), Q^(a) and Q^(b) include those whichare the same as the perfluoroalkyl group having 1 to 6 carbon atomsrepresented by Q^(b1).

The structural unit represented by formula (II-2-A) is preferably astructural unit represented by formula (II-2-A-1):

wherein, in formula (II-2-A-1),

R^(III2), R^(III3), R^(III4), Q^(a), Q^(b), z and ZA⁺ are the same asdefined above,

R^(III5) represents a saturated hydrocarbon group having 1 to 12 carbonatoms, and

X^(I2) represents a divalent saturated hydrocarbon group having 1 to 11carbon atoms, —CH₂— included in the saturated hydrocarbon group may bereplaced by —O—, —S— or —CO—, and a hydrogen atom included in thesaturated hydrocarbon group may be substituted with a halogen atom or ahydroxy group.

Examples of the saturated hydrocarbon group having 1 to 12 carbon atomsrepresented by R^(III5) include linear or branched alkyl groups such asa methyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, ahexyl group, a heptyl group, an octyl group, a nonyl group, a decylgroup, an undecyl group and a dodecyl group.

Examples of the divalent saturated hydrocarbon group represented byX^(I2) include those which are the same as the divalent saturatedhydrocarbon group represented by X^(III3).

The structural unit represented by formula (II-2-A-1) is preferably astructural unit represented by formula (II-2-A-2):

wherein, in formula (II-2-A-2),

R^(III3), R^(III5) and ZA⁺ are the same as defined above, and

m and nA each independently represent 1 or 2.

The structural unit represented by formula (II-2-A′) includes, forexample, the following structural units, structural units in which agroup corresponding to a methyl group of R^(III3) is substituted with analkyl group having 1 to 6 carbon atoms which may have a hydrogen atom, ahalogen atom (e.g., fluorine atom) or a halogen atom (e.g.,trifluoromethyl group, etc.) and the structural units mentioned in WO2012/050015 A. ZA⁺ represents an organic cation.

The structural unit having a sulfonio group and an organic anion in aside chain is preferably a structural unit represented by formula(II-1-1):

wherein, in formula (II-1-1),

A^(II1) represents a single bond or a divalent linking group,

R^(II1) represents a divalent aromatic hydrocarbon group having 6 to 18carbon atoms,

R^(II2) and R^(II3) each independently represent a hydrocarbon grouphaving 1 to 18 carbon atoms, and R^(II2) and R^(II3) may be bonded toeach other to form a ring together with sulfur atoms to which R^(II2)and R^(II3) are bonded,

R^(II4) represents a hydrogen atom, a halogen atom, or an alkyl grouphaving 1 to 6 carbon atoms which may have a halogen atom, and

A⁻ represents an organic anion.

Examples of the divalent aromatic hydrocarbon group having 6 to 18carbon atoms represented by R^(II1) include a phenylene group and anaphthylene group.

Examples of the hydrocarbon group represented by R^(II2) and R^(II3)include an alkyl group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and groups obtained by combining these groups.

Examples of the alkyl group and the alicyclic hydrocarbon group includethose which are the same as mentioned above.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a naphthyl group, an anthryl group, a biphenyl group and aphenanthryl group.

Examples of the combined group include groups obtained by combining theabove-mentioned alkyl group and alicyclic hydrocarbon group, aralkylgroups such as a benzyl group, aromatic hydrocarbon groups having analkyl group (a p-methylphenyl group, a p-tert-butylphenyl group, a tolylgroup, a xylyl group, a cumenyl group, a mesityl group, a2,6-diethylphenyl group, a 2-methyl-6-ethylphenyl group, etc.), aromatichydrocarbon groups having an alicyclic hydrocarbon group (ap-cyclohexylphenyl group, a p-adamantylphenyl group, etc.),aryl-cycloalkyl groups such as a phenylcyclohexyl group, and the like.

Examples of the halogen atom represented by R^(II4) include a fluorineatom, a chlorine atom, a bromine atom and an iodine atom.

Examples of the alkyl group having 1 to 6 carbon atoms which may have ahalogen atom represented by R^(II4) include those which are the same asthe alkyl group having 1 to 6 carbon atoms which may have a halogen atomrepresented by R^(a8).

Examples of the divalent linking group represented by A^(II1) include adivalent saturated hydrocarbon group having 1 to 18 carbon atoms, and—CH₂— included in the divalent saturated hydrocarbon group may bereplaced by —O—, —S— or —CO—. Specific examples thereof include thosewhich are the same as the divalent saturated hydrocarbon group having 1to 18 carbon atoms represented by X^(III3).

Examples of the structural unit including a cation in formula (II-1-1)include the following structural units, structural units in which agroup corresponding to a methyl group of R^(II4) is substituted with ahydrogen atom, a halogen atom (e.g., a fluorine atom, etc.) or an alkylgroup having 1 to 6 carbon atoms which may have a halogen atom (e.g., atrifluoromethyl group, etc.) and the like.

Examples of the organic anion represented by A-include a sulfonic acidanion, a sulfonylimide anion, a sulfonylmethide anion and a carboxylicacid anion. The organic anion represented by A⁻ is preferably a sulfonicacid anion, and examples of the sulfonic acid anion include those whichare the same as an anion represented by formula (B1) mentioned above.

Examples of the sulfonylimide anion represented by A-including thefollowings.

Examples of the sulfonylmethide anion include the followings.

Examples of the carboxylic acid anion include the followings.

Examples of the structural unit represented by formula (II-1-1) includethe followings.

When the structural unit (II) is included in the resin (A), the contentof the structural unit (II) is preferably 1 to 20 mol %, more preferably2 to 15 mol %, and still more preferably 3 to 10 mol %, based on allstructural units of the resin (A).

The resin (A) may include structural units other than the structuralunits mentioned above, and examples of such structural unit includestructural units well-known in the art.

The resin (A) is preferably a resin composed of a structural unit (a1)and a structural unit (s), namely, a copolymer of a monomer (a1) and amonomer (s).

The structural unit (a1) is preferably at least one selected from thegroup consisting of a structural unit (a1-0), a structural unit (a1-1)and a structural unit (a1-2) (preferably the structural unit having acyclohexyl group, or a cyclopentyl group), more preferably at least two,and still more preferably at least two selected from the groupconsisting of a structural unit (a1-1) and a structural unit (a1-2).

The structural unit (s) is preferably at least one selected from thegroup consisting of a structural unit (a2) and a structural unit (a3).The structural unit (a2) is preferably a structural unit represented byformula (a2-1) or a structural unit represented by formula (a2-A). Thestructural unit (a3) is preferably at least one selected from the groupconsisting of a structural unit represented by formula (a3-1), astructural unit represented by formula (a3-2) and a structural unitrepresented by formula (a3-4).

The respective structural units constituting the resin (A) may be usedalone, or two or more structural units may be used in combination. Usinga monomer from which these structural units are derived, it is possibleto produce by a known polymerization method (e.g. radical polymerizationmethod). The content of the respective structural units included in theresin (A) can be adjusted according to the amount of the monomer used inthe polymerization.

The weight-average molecular weight of the resin (A) is preferably 2,000or more (more preferably 2,500 or more, and still more preferably 3,000or more), and 50,000 or less (more preferably 30,000 or less, and stillmore preferably 15,000 or less). In the present specification, theweight-average molecular weight is a value determined by gel permeationchromatography under the conditions mentioned in Examples.

<Resin other than Resin (A)>

The resist composition of the present invention may include resins otherthan the resin (A).

The resin other than the resin (A) includes, for example, a resinincluding a structural unit (a4) or a structural unit (a5) (hereinaftersometimes referred to as resin (X)).

The resin (X) is preferably a resin including a structural unit (a4),particularly.

In the resin (X), the content of the structural unit (a4) is preferably30 mol % or more, more preferably 40 mol % or more, and still morepreferably 45 mol % or more, based on the total of all structural unitsof the resin (X). Examples of the structural unit, which may be furtherincluded in the resin (X), include a structural unit (a2), a structuralunit (a3) and structural units derived from other known monomers.Particularly, the resin (X) is preferably a resin composed only of astructural unit (a4) and/or a structural unit (a5), and more preferablya resin composed only of a structural unit (a4).

The respective structural unit constituting the resin (X) may be usedalone, or two or more structural units may be used in combination. Usinga monomer from which these structural units are derived, it is possibleto produce by a known polymerization method (e.g. radical polymerizationmethod). The content of the respective structural units included in theresin (X) can be adjusted according to the amount of the monomer used inthe polymerization.

The weight-average molecular weight of the resin (X) is preferably 6,000or more (more preferably 7,000 or more) and 80,000 or less (morepreferably 60,000 or less). The measurement means of the weight-averagemolecular weight of the resin (X) is the same as in the case of theresin (A).

When the resist composition includes the resin (X), the content ispreferably 1 to 60 parts by mass, more preferably 1 to 50 parts by mass,still more preferably 1 to 40 parts by mass, yet more preferably 1 to 30parts by mass, and further preferably 1 to 8 parts by mass, based on 100parts by mass of the resin (A).

The content of the resin (A) in the resist composition is preferably 80%by mass or more and 99% by mass or less, and more preferably 90% by massor more and 99% by mass or less, based on the solid component of theresist composition. When including resins other than the resin (A), thetotal content of the resin (A) and resins other than the resin (A) ispreferably 80% by mass or more and 99% by mass or less, and morepreferably 90% by mass or more and 99% by mass or less, based on thesolid component of the resist composition. The solid content of theresist composition and the content of the resin thereto can be measuredby a known analysis means such as liquid chromatography or gaschromatography.

<Solvent (E)>

The content of the solvent (E) in the resist composition is usually 90%by mass or more and 99.9% by mass or less, preferably 92% by mass ormore and 99% by mass or less, and more preferably 94% by mass or moreand 99% by mass or less. The content of the solvent (E) can be measured,for example, by a known analysis means such as liquid chromatography orgas chromatography.

Examples of the solvent (E) include glycol ether esters such asethylcellosolve acetate, ethylcellosolve acetate and propylene glycolmonomethyl ether acetate; glycol ethers such as propylene glycolmonomethyl ether; esters such as ethyl lactate, butyl acetate, amylacetate and ethyl pyruvate; ketones such as acetone, methyl isobutylketone, 2-heptanone and cyclohexanone; and cyclic esters such asγ-butyrolactone. The solvent (E) may be used alone, or two or moresolvents may be used.

<Quencher (C)>

Examples of the quencher (C) include a salt generating an acid having anacidity lower than that of an acid generated from an acid generator (B),and a basic nitrogen-containing organic compound. The content of thequencher (C) is preferably about 0.01 to 15% by mass, more preferablyabout 0.01 to 10% by mass, still more preferably about 0.1 to 8% bymass, and yet more preferably about 0.1 to 7% by mass, based on theamount of the solid component of the resist composition.

<Salt Generating an Acid Having an Acidity Lower than that of an AcidGenerated from the Acid Generator>

The acidity in a salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator (B) is indicated bythe acid dissociation constant (pKa). Regarding the salt generating anacid having an acidity lower than that of an acid generated from theacid generator (B), the acid dissociation constant of an acid generatedfrom the salt usually meets the following inequality: −3<pKa, preferably−1<pKa<7, and more preferably 0<pKa<5.

Examples of the salt generating an acid having an acidity lower thanthat of an acid generated from the acid generator (B) include saltsrepresented by the following formulas, a salt represented by formula (D)mentioned in JP 2015-147926 A (hereinafter sometimes referred to as“weak acid inner salt (D)”, and salts mentioned in JP 2012-229206 A, JP2012-6908 A, JP 2012-72109 A, JP 2011-39502 A and JP 2011-191745 A. Thesalt generating an acid having an acidity lower than that of an acidgenerated from the acid generator (B) is preferably a salt generating acarboxylic acid having an acidity lower than that of an acid generatedfrom the acid generator (B) (salt having a carboxylic acid anion), andmore preferably a weak acid inner salt (D), and still more preferably adiphenyliodonium salt containing a phenyl group substituted with acarboxylic acid anion among the weak acid inner salt (D).

Examples of the weak acid inner salt (D) is preferably adiphenyliodonium salt having an iodonium cation to which two phenylgroups are bonded, and a carboxylic acid anion substituted with at leastone phenyl group of two phenyl groups bonded to the iodonium cation, andspecific examples thereof include a salt represented by the followingformula:

wherein, in formula (D),

R^(D1) and R^(D2) each independently represent a hydrocarbon grouphaving 1 to 12 carbon atoms, an alkoxy group having 1 to 6 carbon atoms,an acyl group having 2 to 7 carbon atoms, an acyloxy group having 2 to 7carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, anitro group or a halogen atom, and

m′ and n′ each independently represent an integer of 0 to 4, and when m′is 2 or more, a plurality of R^(D1) may be the same or different, andwhen n′ is 2 or more, a plurality of R^(D2) may be the same ordifferent.

Examples of the hydrocarbon group as for R^(D1) and R^(D2) include achain hydrocarbon group, an alicyclic hydrocarbon group, an aromatichydrocarbon group, and a group formed by combining these groups.

Examples of the chain hydrocarbon group include alkyl groups such as amethyl group, an ethyl group, a propyl group, an isopropyl group, abutyl group, an isobutyl group, a tert-butyl group, a pentyl group, ahexyl group, a nonyl group and the like.

The alicyclic hydrocarbon group may be either monocyclic or polycyclic,or may be either saturated or unsaturated. Examples thereof includecycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, acyclopentyl group, a cyclohexyl group, a cyclononyl group and acyclododecyl group, a norbornyl group, an adamantyl group and the like.

Examples of the aromatic hydrocarbon group include aryl groups such as aphenyl group, a 1-naphthyl group, a 2-naphthyl group, a 2-methylphenylgroup, a 3-methylphenyl group, a 4-methylphenyl group, a 4-ethylphenylgroup, a 4-propylphenyl group, a 4-isopropylphenyl group, a4-butylphenyl group, a 4-t-butylphenyl group, a 4-hexylphenyl group, a4-cyclohexylphenyl group, an anthryl group, a p-adamantylphenyl group, atolyl group, a xylyl group, a cumenyl group, a mesityl group, a biphenylgroup, a phenanthryl group, a 2,6-diethylphenyl group, a2-methyl-6-ethylphenyl and the like.

Examples of the group formed by combining these groups include analkyl-cycloalkyl group, a cycloalkyl-alkyl group, an aralkyl group(e.g., a phenylmethyl group, a 1-phenylethyl group, a 2-phenylethylgroup, a 1-phenyl-1-propyl group, a 1-phenyl-2-propyl group, a2-phenyl-2-propyl group, a 3-phenyl-1-propyl group, a 4-phenyl-1-butylgroup, a 5-phenyl-1-pentyl group, a 6-phenyl-1-hexyl group, etc.) andthe like.

Examples of the alkoxy group include a methoxy group, an ethoxy groupand the like.

Examples of the acyl group include an acetyl group, a propanoyl group, abenzoyl group, a cyclohexanecarbonyl group and the like.

Examples of the acyloxy group include a group obtained by bonding an oxygroup (—O—) to the above acyl group.

Examples of the alkoxycarbonyl group include a group obtained by bondinga carbonyl group (—CO—) to the above alkoxy group.

Examples of the halogen atom include a fluorine atom, a chlorine atom, abromine atom and the like.

Preferably, R^(D1) and R^(D2) each independently represent an alkylgroup having 1 to 8 carbon atoms, a cycloalkyl group having 3 to 10carbon atoms, an alkoxy group having 1 to 6 carbon atoms, an acyl grouphaving 2 to 4 carbon atoms, an acyloxy group having 2 to 4 carbon atoms,an alkoxycarbonyl group having 2 to 4 carbon atoms, a nitro group or ahalogen atom.

Preferably, m′ and n′ are each independently an integer of 0 to 2, andmore preferably 0, and when m′ is 2 or more, a plurality of R^(D1) maybe the same or different, and when n′ is 2 or more, a plurality ofR^(D2) may be the same or different.

More specifically, the following salts are exemplified.

Examples of the basic nitrogen-containing organic compound include amineand an ammonium salt. Examples of the amine include an aliphatic amineand an aromatic amine. Examples of the aliphatic amine include a primaryamine, a secondary amine and a tertiary amine.

Examples of the amine include 1-naphthylamine, 2-naphthylamine, aniline,diisopropylaniline, 2-, 3- or 4-methylaniline, 4-nitroaniline,N-methylaniline, N,N-dimethylaniline, diphenylamine, hexylamine,heptylamine, octylamine, nonylamine, decylamine, dibutylamine,dipentylamine, dihexylamine, diheptylamine, dioctylamine, dinonylamine,didecylamine, triethylamine, trimethylamine, tripropylamine,tributylamine, tripentylamine, trihexylamine, triheptylamine,trioctylamine, trinonylamine, tridecylamine, methyldibutylamine,methyldipentylamine, methyldihexylamine, methyldicyclohexylamine,methyldiheptylamine, methyldioctylamine, methyldinonylamine,methyldidecylamine, ethyldibutylamine, ethyldipentylamine,ethyldihexylamine, ethyldiheptylamine, ethyldioctylamine,ethyldinonylamine, ethyldidecylamine, dicyclohexylmethylamine,tris[2-(2-methoxyethoxy)ethyl]amine, triisopropanolamine,ethylenediamine, tetramethylenediamine, hexamethylenediamine,4,4′-diamino-1,2-diphenylethane,4,4′-diamino-3,3′-dimethyldiphenylmethane,4,4′-diamino-3,3′-diethyldiphenylmethane, 2,2′-methylenebisaniline,imidazole, 4-methylimidazole, pyridine, 4-methylpyridine,1,2-di(2-pyridyl)ethane, 1,2-di(4-pyridyl)ethane,1,2-di(2-pyridyl)ethene, 1,2-di(4-pyridyl)ethene,1,3-di(4-pyridyl)propane, 1,2-di(4-pyridyloxy)ethane,di(2-pyridyl)ketone, 4,4′-dipyridyl sulfide, 4,4′-dipyridyl disulfide,2,2′-dipyridylamine, 2,2′-dipicolylamine, bipyridine and the like,preferably aromatic amines such as diisopropylaniline, and morepreferably 2,6-diisopropylaniline.

Examples of the ammonium salt include tetramethylammonium hydroxide,tetraisopropylammonium hydroxide, tetrabutylammonium hydroxide,tetrahexylammonium hydroxide, tetraoctylammonium hydroxide,phenyltrimethylammonium hydroxide,3-(trifluoromethyl)phenyltrimethylammonium hydroxide,tetra-n-butylammonium salicylate and choline.

<Other Components>

The resist composition of the present invention may also includecomponents other than the components mentioned above (hereinaftersometimes referred to as “other components (F)”). The other components(F) are not particularly limited and it is possible to use variousadditives known in the resist field, for example, sensitizers,dissolution inhibitors, surfactants, stabilizers and dyes.

<Preparation of Resist Composition>

The resist composition of the present invention can be prepared bymixing a salt (I) and a resin (A), and if necessary, an acid generator(B), resins other than the resin (A), a solvent (E), a quencher (C) andother components (F). The order of mixing these components is any orderand is not particularly limited. It is possible to select, as thetemperature during mixing, appropriate temperature from 10 to 40° C.,according to the type of the resin, the solubility in the solvent (E) ofthe resin and the like. It is possible to select, as the mixing time,appropriate time from 0.5 to 24 hours according to the mixingtemperature. The mixing means is not particularly limited and it ispossible to use mixing with stirring.

After mixing the respective components, the mixture is preferablyfiltered through a filter having a pore diameter of about 0.003 to 0.2μm.

(Method for Producing Resist Pattern)

The method for producing a resist pattern of the present inventioninclude:

(1) a step of applying the resist composition of the present inventionon a substrate,(2) a step of drying the applied composition to form a compositionlayer,(3) a step of exposing the composition layer,(4) a step of heating the exposed composition layer, and(5) a step of developing the heated composition layer.

The resist composition can be usually applied on a substrate using aconventionally used apparatus, such as a spin coater. Examples of thesubstrate include inorganic substrates such as a silicon wafer, andorganic substrates in which a resist film is formed on a surface. Beforeapplying the resist composition, the substrate may be washed, and anorganic antireflection film may be formed on the substrate.

The solvent is removed by drying the applied composition to form acomposition layer. Drying is performed by evaporating the solvent usinga heating device such as a hot plate (so-called “prebake”), or adecompression device. The heating temperature is preferably 50 to 200°C. and the heating time is preferably 10 to 180 seconds. The pressureduring drying under reduced pressure is preferably about 1 to 1.0×10⁵Pa.

The composition layer thus obtained is usually exposed using an aligner.The aligner may be a liquid immersion aligner. It is possible to use, asan exposure source, various exposure sources, for example, exposuresources capable of emitting laser beam in an ultraviolet region such asKrF excimer laser (wavelength of 248 nm), ArF excimer laser (wavelengthof 193 nm) and F₂ excimer laser (wavelength of 157 nm), an exposuresource capable of emitting harmonic laser beam in a far-ultraviolet orvacuum ultra violet region by wavelength-converting laser beam from asolid-state laser source (YAG or semiconductor laser), an exposuresource capable of emitting electron beam or EUV and the like. In thepresent specification, such exposure to radiation is sometimescollectively referred to as “exposure”. The exposure is usuallyperformed through a mask corresponding to a pattern to be required. Whenelectron beam is used as the exposure source, exposure may be performedby direct writing without using the mask.

The exposed composition layer is subjected to a heat treatment(so-called “post-exposure bake”) to promote the deprotection reaction inan acid-labile group. The heating temperature is usually about 50 to200° C., and preferably about 70 to 150° C. It is also possible toperform a chemical treatment (silylation) which adjusts thehydrophilicity or hydrophobicity of the resin on a surface side of thecomposition after heating. Before performing the development, the stepsof application of the resist composition, drying, exposure and heatingmay be repeatedly performed on the exposed composition layer.

The heated composition layer is usually developed with a developingsolution using a development apparatus. Examples of the developingmethod include a dipping method, a paddle method, a spraying method, adynamic dispensing method and the like. The developing temperature ispreferably, for example, 5 to 60° C. and the developing time ispreferably, for example, 5 to 300 seconds. It is possible to produce apositive resist pattern or negative resist pattern by selecting the typeof the developing solution as follows.

When the positive resist pattern is produced from the resist compositionof the present invention, an alkaline developing solution is used as thedeveloping solution. The alkaline developing solution may be variousaqueous alkaline solutions used in this field. Examples thereof includeaqueous solutions of tetramethylammonium hydroxide and(2-hydroxyethyl)trimethylammonium hydroxide (commonly known as choline).The surfactant may be contained in the alkaline developing solution.

It is preferable that the developed resist pattern is washed withultrapure water and then water remaining on the substrate and thepattern is removed.

When the negative resist pattern is produced from the resist compositionof the present invention, a developing solution containing an organicsolvent (hereinafter sometimes referred to as “organic developingsolution”) is used as the developing solution.

Examples of the organic solvent contained in the organic developingsolution include ketone solvents such as 2-hexanone and 2-heptanone;glycol ether ester solvents such as propylene glycol monomethyl etheracetate; ester solvents such as butyl acetate; glycol ether solventssuch as propylene glycol monomethyl ether; amide solvents such asN,N-dimethylacetamide; and aromatic hydrocarbon solvents such asanisole.

The content of the organic solvent in the organic developing solution ispreferably 90% by mass or more and 100% by mass or less, more preferably95% by mass or more and 100% by mass or less, and still more preferablythe organic developing solution is substantially composed of the organicsolvent.

Particularly, the organic developing solution is preferably a developingsolution containing butyl acetate and/or 2-heptanone. The total contentof butyl acetate and 2-heptanone in the organic developing solution ispreferably 50% by mass or more and 100% by mass or less, more preferably90% by mass or more and 100% by mass or less, and still more preferablythe organic developing solution is substantially composed of butylacetate and/or 2-heptanone.

The surfactant may be contained in the organic developing solution. Atrace amount of water may be contained in the organic developingsolution.

During development, the development may be stopped by replacing by asolvent with the type different from that of the organic developingsolution.

The developed resist pattern is preferably washed with a rinsingsolution. The rinsing solution is not particularly limited as long as itdoes not dissolve the resist pattern, and it is possible to use asolution containing an ordinary organic solvent which is preferably analcohol solvent or an ester solvent.

After washing, the rinsing solution remaining on the substrate and thepattern is preferably removed.

(Applications)

The resist composition of the present invention is suitable as a resistcomposition for exposure of KrF excimer laser, a resist composition forexposure of ArF excimer laser, a resist composition for exposure ofelectron beam (EB) or a resist composition for exposure of EUV,particularly a resist composition for exposure of electron beam (EB) ora resist composition for exposure of EUV, and the resist composition isuseful for fine processing of semiconductors.

EXAMPLES

The present invention will be described more specifically by way ofExamples. Percentages and parts expressing the contents or amounts usedin the Examples are by mass unless otherwise specified.

The weight-average molecular weight is a value determined by gelpermeation chromatography. Analysis conditions of gel permeationchromatography are as follows.

Column: TSKgel Multipore HXL-M×3+guardcolumn (manufactured by TOSOHCORPORATION)

Eluent: tetrahydrofuran

Flow rate: 1.0 mL/min

Detector: RI detector

Column temperature: 40° C.

Injection amount: 100 μl

Molecular Weight Standards: Polystyrene Standard (Manufactured by TOSOHCORPORATION)

Structures of compounds were confirmed by measuring a molecular ion peakusing mass spectrometry (Liquid Chromatography: Model 1100, manufacturedby Agilent Technologies, Inc., Mass Spectrometry: Model LC/MSD,manufactured by Agilent Technologies, Inc.). The value of this molecularion peak in the following Examples is indicated by “MASS”.

Example 1: Synthesis of Salt Represented by Formula (I-1)

2.24 Parts of a compound represented by formula (I-1-a), 4.40 parts of acompound represented by formula (I-1-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 2.14 parts of a compoundrepresented by formula (I-1-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 1.56 parts of a compoundrepresented by formula (I-1-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.12 parts of a salt represented by formula (I-1).

MASS (ESI (+) Spectrum): M⁺263.1

MASS (ESI (−) Spectrum): M⁻468.9

Example 2: Synthesis of Salt Represented by Formula (I-2)

2.24 Parts of a compound represented by formula (I-1-a), 9.44 parts of acompound represented by formula (I-2-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 3.37 parts of a compoundrepresented by formula (I-2-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.82 parts of a compoundrepresented by formula (I-2-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.09 parts of a salt represented by formula (I-2).

MASS (ESI (+) Spectrum): M⁺263.1

MASS (ESI (−) Spectrum): M⁻720.7

Example 3: Synthesis of Salt Represented by Formula (I-11)

2.24 Parts of a compound represented by formula (I-1-a), 3.64 parts of acompound represented by formula (I-11-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 1.46 parts of a compoundrepresented by formula (I-11-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 1.37 parts of a compoundrepresented by formula (I-11-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 2.49 parts of a salt represented by formula (I-11).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−431.0

Example 4: Synthesis of Salt Represented by Formula (I-13)

3.01 Parts of a salt represented by formula (I-13-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.82 parts of a compoundrepresented by formula (I-2-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.68 parts of a salt represented by formula (I-13).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−928.8

Example 5: Synthesis of Salt Represented by Formula (I-14)

3.49 Parts of a salt represented by formula (I-14-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.82 parts of a compoundrepresented by formula (I-2-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.57 parts of a salt represented by formula (I-14).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−980.8

Example 6: Synthesis of Salt Represented by Formula (I-19)

3.01 Parts of a salt represented by formula (I-13-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 1.37 parts of a compoundrepresented by formula (I-11-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 2.95 parts of a salt represented by formula (I-19).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−639.1

Example 7: Synthesis of Salt Represented by Formula (I-20)

1.30 Parts of a compound represented by formula (I-20-a), 4.40 parts ofa compound represented by formula (I-1-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 3.68 parts of a compoundrepresented by formula (I-20-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.65 parts of a compoundrepresented by formula (I-20-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.99 parts of a salt represented by formula (I-20).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−686.8

Example 8: Synthesis of Salt Represented by Formula (I-24)

1.82 Parts of a compound represented by formula (I-24-a), 8.80 parts ofa compound represented by formula (I-1-b) and 30 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 3.52 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 4.78 parts of a compoundrepresented by formula (I-24-c).

3.01 Parts of a salt represented by formula (I-13-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 4.75 parts of a compoundrepresented by formula (I-24-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 2.88 parts of a salt represented by formula (I-24).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−1346.8

Example 9: Synthesis of Salt Represented by Formula (I-264)

3.58 Parts of a salt represented by formula (I-264-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.82 parts of a compoundrepresented by formula (I-2-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.12 parts of a salt represented by formula (I-264).

MASS (ESI (+) Spectrum): M+281.0

MASS (ESI (−) Spectrum): M−980.8

Example 10: Synthesis of Salt Represented by Formula (I-281)

2.24 Parts of a compound represented by formula (I-1-a), 7.24 parts of acompound represented by formula (I-281-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 2.92 parts of a compoundrepresented by formula (I-281-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.67 parts of a compoundrepresented by formula (I-281-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.88 parts of a salt represented by formula (I-281).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−610.8

Example 11: Synthesis of Salt Represented by Formula (I-282)

2.24 Parts of a compound represented by formula (I-1-a), 7.24 parts of acompound represented by formula (I-282-b) and 20 parts ofdimethylformamide were mixed, followed by stirring at 23° C. for 30minutes. To the mixture thus obtained, 1.76 parts of potassium carbonatewas added, followed by stirring at 23° C. for 30 minutes and furtherstirring at 90° C. for 3 hours. The mixture thus obtained was cooled to23° C. and then 50 parts of chloroform and 20 parts of ion-exchangedwater were added, and after stirring at 23° C. for 30 minutes, theorganic layer was isolated through separation. To the organic layer thusobtained, 20 parts of ion-exchanged water was added, and after stirringat 23° C. for 30 minutes, the organic layer was isolated throughseparation. This water washing operation was repeated five times. Theorganic layer thus obtained was concentrated and then the concentratedmixture was isolated using a column (silica gel 60N (spherical, neutral)100-210 μm; manufactured by Kanto Chemical Co., Inc., developingsolvent: n-heptane/ethyl acetate=1/1) to obtain 2.74 parts of a compoundrepresented by formula (I-282-c).

2.19 Parts of a salt represented by formula (I-1-d) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.67 parts of a compoundrepresented by formula (I-282-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.32 parts of a salt represented by formula (I-282).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−610.8

Example 12: Synthesis of Salt Represented by Formula (I-17)

3.09 Parts of a salt represented by formula (I-17-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 1.56 parts of a compoundrepresented by formula (I-1-c) was added, followed by stirring at 50° C.for 3 hours and further cooling to 23° C. To the mixture thus obtained,10 parts of an aqueous 5% oxalic acid solution was added, and afterstirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.64 parts of a salt represented by formula (I-17).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−649.0

Example 13: Synthesis of Salt Represented by Formula (I-290)

3.09 Parts of a salt represented by formula (I-17-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.27 parts of a compoundrepresented by formula (I-281-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.33 parts of a salt represented by formula (I-290).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−790.8

Example 14: Synthesis of Salt Represented by Formula (I-291)

3.09 Parts of a salt represented by formula (I-17-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.27 parts of a compoundrepresented by formula (I-282-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 3.89 parts of a salt represented by formula (I-291).

MASS (ESI (+) Spectrum): M+263.1

MASS (ESI (−) Spectrum): M−790.8

Example 15: Synthesis of Salt Represented by Formula (I-625)

4.40 Parts of a salt represented by formula (I-625-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.27 parts of a compoundrepresented by formula (I-281-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 5.11 parts of a salt represented by formula (I-625).

MASS (ESI (+) Spectrum): M+525.0

MASS (ESI (−) Spectrum): M−790.8

Example 16: Synthesis of Salt Represented by Formula (I-670)

4.18 Parts of a salt represented by formula (I-670-a) and 20 parts ofchloroform were mixed, followed by stirring at 23° C. for 30 minutes. Tothe mixed solution thus obtained, 0.89 part of a compound represented byformula (I-1-e) was added, followed by stirring at 50° C. for 2 hours.To the mixed solution thus obtained, 2.27 parts of a compoundrepresented by formula (I-281-c) was added, followed by stirring at 50°C. for 3 hours and further cooling to 23° C. To the mixture thusobtained, 10 parts of an aqueous 5% oxalic acid solution was added, andafter stirring at 23° C. for 30 minutes, the organic layer was isolatedthrough separation. To the organic layer thus obtained, 10 parts ofion-exchanged water was added, and after stirring at 23° C. for 30minutes, the organic layer was isolated through separation. This waterwashing operation was repeated five times. The organic layer thusobtained was concentrated and then 30 parts of tert-butyl methyl etherwas added to the concentrated residue, and after stirring at 23° C. for30 minutes, the supernatant was removed, followed by concentration toobtain 4.89 parts of a salt represented by formula (I-670).

MASS (ESI (+) Spectrum): M+481.0

MASS (ESI (−) Spectrum): M−790.8

Synthesis of Resin

Compounds (monomers) used in synthesis of a resin (A) are shown below.Hereinafter, these compounds are referred to as “monomer (a1-2-6)”according to the formula number.

Synthesis Example 1 [Synthesis of Resin A1]

Using a monomer (a1-2-6), a monomer (a2-1-3), a monomer (a3-4-2) and amonomer (a1-4-2) as monomers, these monomers were mixed in a molar ratioof 53:3:12:32 [monomer (a1-2-6):monomer (a2-1-3):monomer(a3-4-2):monomer (a1-4-2)], and then this monomer mixture was mixed withmethyl isobutyl ketone in the amount of 1.5 mass times the total mass ofall monomers. To the mixture thus obtained, azobisisobutyronitrile andazobis(2,4-dimethylvaleronitrile) as initiators were added in theamounts of 1.2 mol % and 3.6 mol % based on the total molar number ofall monomers, followed by heating at 73° C. for about 5 hours.Thereafter, to the polymerization reaction solution thus obtained, anaqueous p-toluenesulfonic acid solution (2.5% by weight) was added inthe amount of 2.0 mass times the total mass of all monomers, followed bystirring for 12 hours and further isolation through separation. Theorganic layer thus obtained was poured into a large amount of n-heptaneto precipitate a resin, followed by filtration and recovery to obtain aresin A1 having a weight-average molecular weight of about 5.3×10³ in ayield of 88%. This resin A1 has the following structural units.

Synthesis Example 2 [Synthesis of Resin A2]

Using a monomer (a1-2-6), a monomer (a2-1-3), a monomer (a3-4-2) and amonomer (a1-4-13) as monomers, these monomers were mixed in a molarratio of 53:3:12:32 [monomer (a1-2-6):monomer (a2-1-3):monomer(a3-4-2):monomer (a1-4-13)], and then this monomer mixture was mixedwith methyl isobutyl ketone in the amount of 1.5 mass times the totalmass of all monomers. To the mixture thus obtained,azobisisobutyronitrile and azobis(2,4-dimethylvaleronitrile) asinitiators were added in the amounts of 1.2 mol % and 3.6 mol % based onthe total molar number of all monomers, followed by heating at 73° C.for about 5 hours. Thereafter, to the polymerization reaction solutionthus obtained, an aqueous p-toluenesulfonic acid solution (2.5% byweight) was added in the amount of 2.0 mass times the total mass of allmonomers, followed by stirring for 12 hours and further isolationthrough separation. The organic layer thus obtained was poured into alarge amount of n-heptane to precipitate a resin, followed by filtrationand recovery to obtain a resin A2 having a weight-average molecularweight of about 5.1×10³ in a yield of 79%. This resin A2 has thefollowing structural units.

<Preparation of Resist Composition>

As shown in Table 2, the following components were mixed and the mixturethus obtained was filtered through a fluororesin filter having a porediameter of 0.2 μm to prepare resist compositions.

TABLE 2 Resist Acid composition Resin Salt (I) generator Quencher PB/PEBComposition A1 = I-1 = — C1 = 100° C./ 1 10 parts 1.5 parts 0.35 part130° C. Composition A1 = I-2 = — C1 = 100° C./ 2 10 parts 1.5 parts 0.35part 130° C. Composition A1 = I-11 = — C1 = 100° C./ 3 10 parts 1.5parts 0.35 part 130° C. Composition A1 = I-13 = — C1 = 100° C./ 4 10parts 1.5 parts 0.35 part 130° C. Composition A2 = I-13 = — C1 = 100°C./ 5 10 parts 1.5 parts 0.35 part 130° C. Composition A2 = I-13 = — D1= 100° C./ 6 10 parts 1.5 parts 0.35 part 130° C. Composition A1 = I-14= — C1 = 100° C./ 7 10 parts 1.5 parts 0.35 part 130° C. Composition A1= I-19 = — C1 = 100° C./ 8 10 parts 1.5 parts 0.35 part 130° C.Composition A1 = I-20 = — C1 = 100° C./ 9 10 parts 1.5 parts 0.35 part130° C. Composition A1 = I-24 = — C1 = 100° C./ 10 10 parts 1.5 parts0.35 part 130° C. Composition A1 = I-264 = — C1 = 100° C./ 11 10 parts1.5 parts 0.35 part 130° C. Composition A1 = I-281 = — C1 = 100° C./ 1210 parts 1.5 parts 0.35 part 130° C. Composition A1 = I-282 = — C1 =100° C./ 13 10 parts 1.5 parts 0.35 part 130° C. Composition A1 = I-17 =— C1 = 100° C./ 14 10 parts 1.5 parts 0.35 part 130° C. Composition A1 =I-290 = — C1 = 100° C./ 15 10 parts 1.5 parts 0.35 part 130° C.Composition A1 = I-291 = — C1 = 100° C./ 16 10 parts 1.5 parts 0.35 part130° C. Composition A1 = I-625 = — C1 = 100° C./ 17 10 parts 1.5 parts0.35 part 130° C. Composition A1 = I-670 = — C1 = 100° C./ 18 10 parts1.5 parts 0.35 part 130° C. Comparative A1 = — IX-1 = C1 = 100° C./Composition 1 10 parts 1.5 parts 0.35 part 130° C. Comparative A1 = —IX-2 = C1 = 100° C./ Composition 2 10 parts 1.5 parts 0.35 part 130° C.Comparative A1 = — IX-3 = C1 = 100° C./ Composition 3 10 parts 1.5 parts0.35 part 130° C. Comparative A1 = — IX-4 = C1 = 100° C./ Composition 410 parts 1.5 parts 0.35 part 130° C.

<Resin>

A1, A2: Resin A1, Resin A2

<Salt (I)>

I-1: Salt represented by formula (I-1)

I-2: Salt represented by formula (I-2)

I-11: Salt represented by formula (I-11)

I-13: Salt represented by formula (I-13)

I-14: Salt represented by formula (I-14)

I-17: Salt represented by formula (I-17)

I-19: Salt represented by formula (I-19)

I-20: Salt represented by formula (I-20)

I-24: Salt represented by formula (I-24)

I-264: Salt represented by formula (I-264)

I-281: Salt represented by formula (I-281)

I-282: Salt represented by formula (I-282)

I-290: Salt represented by formula (I-290)

I-291: Salt represented by formula (I-291)

I-625: Salt represented by formula (I-625)

I-670: Salt represented by formula (I-670)

<Acid Generator>

IX-1

IX-2

IX-3

IX-4

<Quencher>

C1: synthesized by the method mentioned in JP 2011-39502 A

D1: (manufactured by Tokyo Chemical Industry Co., Ltd.)

<Solvent>

Propylene glycol monomethyl ether acetate 400 parts Propylene glycolmonomethyl ether 100 parts γ-Butyrolactone  5 parts(Evaluation of Exposure of Resist Composition with Electron Beam)

Each 6 inch-diameter silicon wafer was treated with hexamethyldisilazaneon a direct hot plate at 90° C. for 60 seconds. A resist composition wasspin-coated on the silicon wafer in such a manner that the thickness ofthe composition layer became 0.04 μm. Then, the coated silicon wafer wasprebaked on the direct hot plate at the temperature shown in the column“PB” of Table 2 for 60 seconds to form a composition layer. Using anelectron-beam direct-write system (“ELS-F125 125 keV”, manufactured byELIONIX INC.), contact hole patterns (hole pitch of 40 nm/hole diameterof 17 nm) were directly written on the composition layer formed on thewafer while changing the exposure dose stepwise.

After exposure, post-exposure baking was performed on the hot plate atthe temperature shown in the column “PEB” of Table 2 for 60 seconds.Next, the composition layer on this silicon wafer was developed withbutyl acetate (manufactured by Tokyo Chemical Industry Co., Ltd.) as adeveloping solution at 23° C. for 20 seconds by the dynamic dispensemethod to obtain a resist pattern.

In the resist pattern obtained after development, the exposure dose atwhich the diameter of holes formed became 17 nm was regarded aseffective sensitivity.

<Evaluation of CD Uniformity (CDU)>

In the effective sensitivity, the hole diameter of the pattern formedwith a hole dimeter of 17 nm was determined by measuring 24 times perone hole and the average of the measured values was regarded as theaverage hole diameter. The standard deviation was determined under theconditions that the average diameter of 400 holes about the patternsformed with a hole dimeter of 17 nm in the same wafer was regarded to aspopulation.

The results are shown in Table 3. The numerical value in the tablerepresents the standard deviation (nm)

TABLE 3 Resist composition CDU Example 17 Composition 1 2.70 Example 18Composition 2 2.63 Example 19 Composition 3 2.77 Example 20 Composition4 2.53 Example 21 Composition 5 2.47 Example 22 Composition 6 2.42Example 23 Composition 7 2.58 Example 24 Composition 8 2.68 Example 25Composition 9 2.64 Example 26 Composition 10 2.60 Example 27 Composition11 2.72 Example 28 Composition 12 2.51 Example 29 Composition 13 2.55Example 30 Composition 14 2.52 Example 31 Composition 15 2.33 Example 32Composition 16 2.36 Example 33 Composition 17 2.25 Example 34Composition 18 2.29 Comparative Example 1 Comparative Composition 1 2.85Comparative Example 2 Comparative Composition 2 2.80 Comparative Example3 Comparative Composition 3 2.90 Comparative Example 4 ComparativeComposition 4 2.88

As compared with Comparative Compositions 1 to 4, Compositions 1 to 18exhibited small standard deviation and satisfactory evaluation of CDuniformity (CDU).

A resist composition including a salt of the present invention hassatisfactory CD uniformity (CDU), and is therefore useful for fineprocessing of semiconductors.

1. A salt represented by formula (I):

wherein, in formula (I), Q¹ and Q² each independently represent afluorine atom or a perfluoroalkyl group having 1 to 6 carbon atoms, R¹¹and R¹² each independently represent a hydrogen atom, a fluorine atom ora perfluoroalkyl group having 1 to 6 carbon atoms, z represents aninteger of 0 to 6, and when z is 2 or more, a plurality of R¹¹ and R¹²may be the same or different from each other, X⁰ represents *—CO—O—,*—O—CO—, *—O—CO—O— or *—O—, and * represents a bonding site toC(R¹¹)(R¹²) or C(Q¹)(Q²), L¹ represents a single bond or a hydrocarbongroup having 1 to 28 carbon atoms which may have a substituent, and—CH₂— included in the hydrocarbon group may be replaced by —O—, —S—,—SO₂— or —CO—, Ar represents an aromatic hydrocarbon group having 6 to18 carbon atoms which may have a substituent, X¹ represents an oxygenatom or a sulfur atom, R¹ represents a halogen atom or a haloalkyl grouphaving 1 to 12 carbon atoms, R² represents a halogen atom, a hydroxygroup, a haloalkyl group having 1 to 12 carbon atoms or an alkyl grouphaving 1 to 12 carbon atoms, and —CH₂— included in the haloalkyl groupand the alkyl group may be replaced by —O— or —CO—, m1 represents aninteger of 1 to 6, and when m1 is 2 or more, a plurality of groups inparentheses may be the same or different from each other, m2 representsan integer of 0 to 4, and when m2 is 2 or more, a plurality of R² may bethe same or different from each other, and Z⁺ represents an organiccation.
 2. The salt according to claim 1, wherein L¹ represents a singlebond or *-L2-CO—O—, wherein L² represents a cyclic hydrocarbon grouphaving 3 to 18 carbon atoms or a group obtained by combining a cyclichydrocarbon group having 3 to 18 carbon atoms with an alkanediyl grouphaving 1 to 4 carbon atoms, the cyclic hydrocarbon group may have asubstituent, —CH₂— included in the cyclic hydrocarbon group may bereplaced by —O—, —S—, —CO— or —SO₂—, —CH₂— included in the alkanediylgroup may be replaced by —O— or —CO—, and * represents a bonding site toX⁰.
 3. The salt according to claim 1, wherein Ar is an aromatichydrocarbon group having 6 to 10 carbon atoms which may have asubstituent.
 4. The salt according to claim 1, wherein X¹ is an oxygenatom.
 5. The salt according to claim 1, wherein R¹ is an iodine atom, afluorine atom or a perfluoroalkyl group having 1 to 3 carbon atoms. 6.The salt according to claim 1, wherein R² is an iodine atom, a fluorineatom, a hydroxy group, a perfluoroalkyl group having 1 to 3 carbon atomsor an alkoxy group having 1 to 3 carbon atoms.
 7. An acid generatorcomprising the salt according to claim
 1. 8. A resist compositioncomprising the acid generator according to claim 7 and a resin having anacid-labile group.
 9. The resist composition according to claim 8,wherein the resin having an acid-labile group includes at least oneselected from the group consisting of a structural unit represented byformula (a1-0), a structural unit represented by formula (a1-1) and astructural unit represented by formula (a1-2):

wherein, in formula (a1-0), formula (a1-1) and formula (a1-2), L^(a01),L^(a1) and L^(a2) each independently represent —O— or*—O—(CH₂)_(k1)—CO—O—, k1 represents an integer of 1 to 7, and *represents a bonding site to —CO—, R^(a01), R^(a4) and R^(a5) eachindependently represent a hydrogen atom, a halogen atom, or an alkylgroup having 1 to 6 carbon atoms which may have a halogen atom, R^(a02),R^(a03) and R^(a04) each independently represent an alkyl group having 1to 8 carbon atoms, an alicyclic hydrocarbon group having 3 to 18 carbonatoms, an aromatic hydrocarbon group having 6 to 18 carbon atoms, or agroup obtained by combining these groups, R^(a6) and R^(a7) eachindependently represent an alkyl group having 1 to 8 carbon atoms, analkenyl group having 2 to 8 carbon atoms, an alicyclic hydrocarbon grouphaving 3 to 18 carbon atoms, an aromatic hydrocarbon group having 6 to18 carbon atoms, or a group formed by combining these groups, m1represents an integer of 0 to 14, n1 represents an integer of 0 to 10,and n1′ represents an integer of 0 to
 3. 10. The resist compositionaccording to claim 8, wherein the resin having an acid-labile groupincludes a structural unit represented by formula (a2-A):

wherein, in formula (a2-A), R^(a50) represents a hydrogen atom, ahalogen atom, or an alkyl group having 1 to 6 carbon atoms which mayhave a halogen atom, R^(a51) represents a halogen atom, a hydroxy group,an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6carbon atoms, an alkoxyalkyl group having 2 to 12 carbon atoms, analkoxyalkoxy group having 2 to 12 carbon atoms, an alkylcarbonyl grouphaving 2 to 4 carbon atoms, an alkylcarbonyloxy group having 2 to 4carbon atoms, an acryloyloxy group or a methacryloyloxy group, A^(a50)represents a single bond or * —X^(a51)-(A^(a52)-X^(a52))_(nb)—, and *represents a bonding site to carbon atoms to which —R^(a50) is bonded,A^(a52) represents an alkanediyl group having 1 to 6 carbon atoms,X^(a51) and X^(a52) each independently represent —O—, —CO—O— or —O—CO—,nb represents 0 or 1, and mb represents an integer of 0 to 4, and whenmb is an integer of 2 or more, a plurality of R^(a51) may be the same ordifferent from each other.
 11. The resist composition according to claim8, further comprising a salt generating an acid having an acidity lowerthan that of an acid generated from the acid generator.
 12. A method forproducing a resist pattern, which comprises: (1) a step of applying theresist composition according to claim 8 on a substrate, (2) a step ofdrying the applied resist composition to form a composition layer, (3) astep of exposing the composition layer, (4) a step of heating theexposed composition layer, and (5) a step of developing the heatedcomposition layer.